Hi and welcome
You sound like the kind of loving and caring owner who tends to not fall short in terms of care at all but who tends to overthink things because they fear making mistakes and have unrealistic expectations of themselves as a result of the enormous pressure to fit in on social media at all times in order to avoid being bullied. The kind of owner who would rather let them go to another place because they themselves feel defective in their care.
Rest assured that you are not failing your piggies or yourself. What is failing you are unquestioned unrealistic expectations, a low self-esteem as the result of the bullying culture that is currently taking over and the fear to do wrong as a result.
When in fact you learn so much more and more deeply from not getting it right all the time and developing a constructive attitude towards mistakes.
In the end, as a human you do not grow by confining yourself to a safe box; you grow by learning how to get up after a stumble and - as long as you keep making the same mistake - you become a lot more resilient in terms of your own self-respect and but also emotionally mature and much more understanding of the motivations and emotions of others. And you may even learn to be proud of your own growth, how far you have come, be more confident in yourself and learn to trust your instincts as you go through life.
Try to embrace finding your own constructive solutions to problems, don't be afraid if they are not always working out and always question whether what you see on social media is the real, full picture and whether what the online bullies say is actually true and not just for their own gratification and justification or fear of being found out themselves.
Or whether they are just thoughtlessly handing on advice as self-nominated 'experts' that they have no personal experience with and can therefore not judge whether it is right or appropriate.
Unfortunately, social media have also promoted a very unrealistic image of guinea pigs because what they present is in fact entirely human interest and is not pet species driven - who really likes to watch squirming and tweaking piggies, which represent the reality and majority of piggies?
There are some true cuddle piggies but they are actually the exception and not the rule. It also takes months and in some cases even years to win a nervous piggy's trust - often you only notice that you have actually got it when they respond to you during an illness and medication.
And in that area (medical information for guinea pigs) what you'll inevitably find online are all the horror stories and the miracle cures but not the unexciting problem-free recovered; the huge wodge of 'normality' is just taken for granted and is not considered worth mentioning.
Even on this forum there is not a full proportional representation when you do your searches because we are contacted about often complex and serious illness support where the standard vet care is not working and not just by regular members with an ill piggy.
We can help with moral support and practical care tips but we can unfortunately (and are legally not allowed to) replace veterinary care, and with our advice we go strictly by our collective forum or personal experiences.
However, you can have a great relationship with your piggies by entering their world instead of training them to sit still and be bored with you on the sofa and share their fun within their own world - this puts your interaction on a whole new level and you can build up on that to bring them out fully because each piggy is different and has their own quirks.
You may find our Enrichment guide with lots of ideas for how many areas of enriched interaction are possibe helpful - generally, the simpler and the more piggies can let loose their destructive side, the better. Expensive toys from the shop are usually ignored but having to work to get at their food is so much more fun.
This kind of inter-species interacting where you are a participant and watcher goes quite a long way to build up trust but it also opens up a much wider world for you to form a bond that is not human-centric but where your piggies can show you who they are - and you can share the fun together.
Enrichment Ideas for Guinea Pigs
As to what your piggies have come from, you may find this thread here rather thought provoking:
Arrival in a home from the perspective of pet shop guinea pigs
Please be assured that we are a friendly and supportive place; we look after owners as much as their piggies and we respect each other. What we offer is a community in which you can ask any question, as consequential or 'silly' as may be (silly questions are actually the most thought provoking ones and anything but 'silly). You can be assured a friendly and helpful answer or ongoing support during stressful settling in, bonding, illness or end of life/bereavement times. Our own information is based on our nearly 20 years of collective experiences and questions. We are doing all this for free in our own free time and anybody is welcome to join our community.
We have actually really tested what is making the round online as to whether it works or not and all of that has and still is going into our forum guides. The guide format allows us to add and update our extensive information resource so - unlike books - it is not outdated but new developments and real-life practical experiences with them are going to make their way into them. Since we cannot repeat everything in full in every thread, we link in our guides for further practical how-to tips, advice or in-depth information into our posts.
But you may find our New Owners information collection very helpful for bookmarking, browsing, reading and re-reading as you go along since you will pick up on different things at different levels of experience.
Getting Started - Essential Information for New Owners
I hope that this helps you? No question or problem is too small to be asked, and you can always assured that there are quite a number who have the same question but not the courage...

Our Care sections, especially our Support Corners, are monitored by staff to ensure as much as possible that they are answered when one of us is coming on.
The Chat sections are for that; for talking about our piggies, other pets or anything else. Quite a number of our forum regulars have a little blog thread for their piggies and some other pets. You are welcome to do it for your own but we recommend to bookmark any blog or ongoing support thread so you can always pick it up easily again.