Sounds like you are doing fine with the feeding.
Personally I don't like to see a piggie on their own - they love company of their own kind and you will love the way they "Talk" to each other. How about getting a really tame one or a baby to put in another cage next to the one you have now for a few days until you are good friends with the new one. Then the one you have now can gain confidence from that too.
One more thing - piggies can't make their own vitamin D, just like us, so they need a supplement, or even better, plenty of fresh air and sunshine.