Girlfriends sex drive lowered, is it my performance or birth control? ( M18, F18 )

At the start of my relationship with my girlfriend, we were absolute animals, multiple times every day.

then one weekend i stopped performing as well ( lasting a lot shorter), and after i continued to last shorter than i used to, we started having a lot less sex, she was simply not as horny anymore.

at first, i tied it down to me not performing, she didn't want it anymore because it wasn't as good as it used to, but then i remembered, all of this happened around the same time as she changed to another birth control. i did some research and found that birth control is known to lower sex drive.

the only thing is she was on birth control before, so why was it so high before? is it possible just a different birth control can change it more than the other one?

so just looking for advice, do you think it's the birth control or is it me?