Hi Shelley,
I know that nail clipping can be traumatic. My heart was in my mouth the first time I done it. Do your piggies have black nails?
To put your mind at rest, get some styptic powder and keep it by your side. If the worst happens a dab of that will stop the bleeding straight away. If you can't get the powder, running the toe under running cold water will stop the bleeding.
Also, the piggie will usually squeak if it feels any pressure on the quick so you can do a careful test squeeze first.
Invest in some small animal nail clippers. I got mine for 99p on ebay. They are fab.
Good luck
xx