Please weigh the little piggy. In the UK the standard age/weight for weaning for males is 3 weeks, females stay until they have reached the rehoming weight of 400g at 6-8 weeks.
The rehoming age/weight for both sexes is as above.
To ensure she is getting the correct balance of nutrients for good growth please give pellets/nuggets - you can soak a small amount in warm water to soften so they are easier to eat. A bowl of dry pellets available at all times, water in a bottle low enough for her to reach easily, and plenty of hay with a small handful of alfalfa/lucerne daily as this contains a rich source of calcium. Only small amounts of veg as she is so tiny and she needs to fill up on the pellets for good growth.
Suzy x