Hi there,
i don't wish to sound hurtful but I'm pretty sure you were given lots of advice on another thread regarding the sex of your guinea pig and advised the best way of how to find a new friend, just going out and buying another pig isn't the easy way because there is no guarantee they will get on and doing a bonding session does require a good eye for what to look for. Frankly, I didn't do a bonding session for many years after keeping them, I relied upon the experts.
However now you've got a problem, a) because you are not quite sure what kind of behaviour you are looking at b) there was no quarantine time, usually 2 weeks.
If you are in the UK i would suggest you find a local rescue close by whom can either help you with the bonding session or and this is going to sound mean - return the baby from where you bought her and use a rescue instead. I know it sounds mean but honestly its the best way. Your baby piggy is going to be scared, its been taken from a home it knows and plonked in with another pig it doesn't know, just like humans there are no guarantees they will get on.
For the time being, I would get a cardboard box put bedding, something soft for the baby piggy, water and hay and put the baby piggy in there for the night.
Can you add your location i.e. country & county at least.
Also you may wish to look at the thread on how to handle and pick up guinea pigs also.
Good luck