As the title says really....
Sorry in advance if this is tmi.
I have always had pretty rubbish sex lives. With the exception of my dc father my other long term relationships have always gone through phases of very irregular and sometimes frankly bad sex. My current partner who I'm engaged to has a lower libido than me so we don't do it often but when we do it's always the same position (me on top 

) and I feel like I don't have the best rhythm or movement. He hasn't said anything but tends to try to move me around a bit. And without being graphic I always have to finish him with my hand.
I'm starting to feel like I'm the problem here. I'm not sexually confident. I wish I could have some allure or sass about me but it's just not me. I'm fairly happy with a vanilla sex life but it feels like I'm not even very good at that and maybe my rubbish sexual history has been due to me being crap!
Don't get me wrong I enjoy sex with my partner but I feel like he's not enjoying it and that puts me on edge.