Girlfriend won't touch me during sex *lesbian

Hi i'm female ,18 just recently started dating another female she's 17, we started seeing each other around 2 months ago. My ex introduced me to her when we were dating, so at first we were mates and then after my ex and i broke up, we got drunk one night and had sex. (Btw my ex is totally cool with it all and she's in another relationship now) ever since we've started seeing each other whenever we have sex, she barely touches me, i always just end up satisfying her and never get anything in return. At first this didn't bother as i thought she was just shy and eventually she'd build confidence with me.
But now we're in a relationship i think its been long enough and i need to speak to her about it but im a bit nervous.
She has only ever had sex with one other girl and she dated a guy for a year before me. But as for me im a lot more experienced with girls so i'm thinking she's possibly really nervous and doesn't know what to do.
She knows i have trouble climaxing with other people although she is the same.
Even tho she's like that i still try my best to make her feel good, even if she doesn't cum.
I really like her and i think that's why ive just let it slip but its starting to get to me especially after hearing how good she was at making her male ex feel good in bed.
She's perfectly fine with everything else like: cuddling, making out and showing affection. Its only when it comes to sex she shy's away.
Just not sure how to approach this one.
Thank you guys )))