Yes, birth control has hormones in it that can crash her sex drive.
Most women need a lot of foreplay and a lot of them cannot have an orgasm through intercourse alone. Has she ever had an orgasm? If not, she's probably as clueless as you are about how to give her one.
Can you tell me what you're trying so I can get an idea of where you're coming from? Try watching her reactions when you touch her, if she's not a moaner, listen to her breathing. Pay attention to what makes her gasp, what makes her stomach muscles tremble.
Is she nervous about sex or does she jump you and just not know how to cum?
Try having her lie on her back and lightly run your hands up and down her body. Watch for goose-bumps
and tease the hell out of her: just brush her nipples, run your hand
just to the top of her vulva, but don't actually touch her clit. Nibble lightly on her neck and ears, both are usually erogenous zones for girls. You basically want a whimpering, begging mess of a woman before you even start touching her clit.
That brings me to the clit: some are
VERY sensitive. It may take awhile to figure out how to touch hers. Try lightly tracing circles around it, or an up and down motion over it. If she's moaning, that's good- jerking in spasms (unless she's cumming) means you're touching it wrong. Mine for instance if you go side to side is waaay too intense.
Oral is awesome for girls (to receive). Don't just lick the clit, suck on it and flick your tongue against it: she will thank you.
When you're inside of her, position your body so that the shaft of your cock slides against her clit with every stroke.
Most of all, keep trying: you will get it right eventually.
