People have different sex drives. A 'low' one or a 'high' one is neither normal nor abnormal, unless it interferes with your relationships and/or life. It's about compromise. Make sure your boyfriend recognizes that just because you don't want sex every night, it really doesn't mean you don't want him. Some people just don't have the drive, it's as simple as that. There are many times where lack of sex has absolutely nothing to do with the feelings for the other person. But make sure that is not the case. If there is anything bothering you about him or your relationship, address it. If you don't, your sex drive will never increase (with him, at least). Now that that is out of the way, here are some things to try.
One thing is to change the birth control. Different birth controls can give off different hormones and in different ways. May something that lets off a low-dose of hormones over the course of the month, such as an IUD, might help you. Or if you are on a pill that gives you only a few periods a year, maybe going back to a period a month would be good, as many girls get horny before/during their periods. If you really don't want to change though, which is understandable, there are things you can do.
First, you could try a cream. Pure Romance sells an enhancement cream called 'Ex-T-Cee.' It's a minty cream that you apply to the clitoris, and when air hits the minty-stuff it makes you all tingly and turned on. Even if you aren't in the mood, that'll do it for you.
Second, depression not only affects your mood throughout the day, but it also can affect your sex drive. If you are stressed or depressed in general, your sex drive will greatly decrease. If you know you will be spending a night together, try to do something low-key that will relax you. Have your boyfriend give you a massage or go on a little trip somewhere for a day or a night, just to get away from your cares for a little bit. Light some candles, turn off your phone, and make sure you don't have any work to do for a night. Try to focus just on your partner; what do you find attractive about him, what do you love about him? Try to block out any thoughts of work, school, money, to-do things...
Third, try exercise!! Exercise can reduce stress and anxiety and make you healthier. Exercising releases feel-good hormones, and these kinds of hormones can keep you in a good mood and even make you feel frisky. Not only that, but working out may make you feel better about yourself, in turn making you feel sexier and wanting to show it off in the bedroom. Make sure you're eating healthy and keeping yourself hydrated. Any kind of physical problem will likely overshadow any sexual feelings you might have.
And lastly, have fun with sex!! If you have a hard time getting turned on, look at your sex life. Do you have it in one or two positions every Tuesday night on your living room floor? Try a different night, a different room, a new position. Try spontaneous sex, try role-playing, watch porn, read erotica. Not everyone is able to get aroused from the same thing or same person each time, and sometimes we have to mix it up a bit to get ourselves going. Discuss it with your partner and tell him you want his help. And make sure there's lots of foreplay. If you think you have decent foreplay, have even more. If after trying different ways to increase it, and it doesn't work, go talk to your doctor. It could be any combination of things, and they may be able to help you better than an online blogger :P.Good luck!!
MSN Health Article.