What is the problem here whats is wrong with her ?

Well it's definitely not the right time to ask her to marry you! That would look like you don't take the problems seriously. She could be playing you, or she could just be lonely. But I think it's most likely that she is scared and confused about getting back into a serious relationship with you. Things obviously went badly wrong the first time round. If she's worth waiting for then give it time - you've only been back in contact for a few weeks, that's very little time for a woman with a young baby to make a life changing decision about her future.