Tell her that, while you think she's a great gal and care for her, your needs are important too. That its unusual not to be having sex after 7 months. Say you understand her issues about her first time but that you are not that guy. Say you are thinking of breaking it off to find someone more in tune with her sexuality. Emphasize you understand her reasons and you are not going to pressure her, but that you think breaking it off might be for the best b/c you two are clearly on different pages about the issue.
Stick to "I statements" (look this up if you don't know about it). Avoid accusing her of anything. State your case calmly from the perspective of YOUR needs.
BTW, even if you do stay together, this issue will set a boundary for how your needs get met with this gal on other issues. Its important, in other words, and well worth the chance you may break up over this. Good luck.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh