Advice please? Dating please help?

Ok so I'm 14 but I look alot older like 18 and there's this 21 year old at this university that I'm attending for extra credit for Spanish this summer and she always tries to talk to me everychance she gets and I know she's infatuated with me as I am with her but should I tell her how old I am? Or just Kiss her and spend time with her without her knowing ? I don't wanna be shallow and keep it secret but we get all excited and I can feel the ual tension when we talk I don't want it to stop either :( ehh