@INTAPF,
I think it would be best to remain work friends. You may just be a little infatuated because she talks to you,but many people just like to converse and are naturally friendly. There is nothing wrong with asking her, but she does have a 4 year old.....you're only 20....she needs to support and raise her child.
I know this sounds negative, but you also could be at risk because of the age difference. She may be wonderful and incredibly well adjusted but she could also exploit your youthfulness and (pleas don't be insulted) but the imbalance of your life experience. Very young people never want to hear this, but I'm not implying you are immature...I'm saying the older individual could be immature and that has the potential to tie you in knots in ways you can't imagine.
If you were my brother or sister I would encourage you to mix with people closer to your age. I've always enjoyed people younger and older and the same age. That can be enriching, just be careful to keep a comfortable distance for awhile. She's only worked with you or a few weeks....give it a little more time.
That's just my suggestion.