How old is she?
Micro isn't a separate breed, it's just a marketing term. I don't know a lot about pig breeds, but with her black body and wee white legs/face stripe, she could possibly be from Berkshire stock? Does she have white on her tail, it's hard to tell? If you know both parents were very small, then likely the child will be small, but honestly, there's a lot of dishonesty out there - if you don't know the parents, I'd suggest her eventual size is pot luck. Although if you figure out the breed, research their average size.