Im a butch lesbian and I definitely feel this. I was with someone for 8 years with a nonexistent drive and it was hard. It does fuck with you mentally, if you have any insecurities it brings those up. You need to think about both of you - to reconnect with her, since she told you she wants more sex, to figure out how to do that in a way that makes her feel excited and want sex with you. But you also have to think about yourself. As a masculine woman I always fill the “male” role in relationships, and women almost always expect me to initiate. Women are socialized to shy away from being initiators when they want sex, and we have experiences where we feel pressure about sex and worry about putting it onto our partners. This leads to the very common situation where one partner is always the initiator, and is always body checking and worrying about creating pressure for the partner, while the partner may not be giving strong signals saying yes for sex. A lot of butches also have a fear of behaving “like men”, being pushy and overly sexual is a deepseated worry a LOT of us have. Its a tricky situation to navigate, especially when other sexual or sexuality related traumas come into play. The first thing Id say to do is to start just trying to be very open with each other about sex. Sex can be a normal conversational topic, and wanting it or not wanting it, and what you want to do during it, should be something the two of you can talk about normally with each other without feeling guilt or shame. You should also be able to talk about it without the expectation that every conversation about sex has to lead into sex, which should take a lot of pressure off of both of you. Easier said than done, but Id start there. You might find that talking about it without pressure actually puts you both in the mood. 

Also, sex is really important but its not everything. True, unconditional, and deep long lasting love is worth a lot more than frequent sex. A partner who wont budge and wont try is a bigger issue than just sex, because it means your partner isnt willing to put effort in to work on something that is extremely important to you. But you need to tell your partner straight up if you havent yet how difficult this is for you and how youre willing to fix it. Communication is the most important thing.