Use a second form of birth control. Since condoms aren't 100%, it is a wise choice anyway.

Get an intra-uterine device (IUD). You can get the one with hormones or the copper one without hormones and then I assure you that you won't have to worry about getting pregnant. Also, you should ALWAYS use lube with the condom, and not just the pre-lubed kind. Buy a bottle and use it regularly. This will keep the condom from breaking inside you. Trust me, you don't want to go fishing for the top of the condom because all he pulled out with was the ring and some tattered condom remains. It's not so much the gross factor, because that's really not that gross, but the worry factor is a real bitch. So yeah, if you use the condoms properly, with a new one for each erection, making sure you don't put it on until he's already rock-hard, and always using just one, you should be okay. Also, don't use Kimono brand condoms- they break. Yeah, so I've actually never had cum leak out before. If you're really worried, you can touch the offending liquid and smell it. If it had cum in it, you'd be able to smell it. Yeah, condoms are 98% effective when used properly, so between those two methods, you won't have to worry about getting pregnant, and if you educate yourself on STD's and keep using the condoms properly, you can keep those worries to a minimum as well. If you go down to Planned Parenthood, they will be more than happy to tell you anything you want to know about all the STDs and proper prevention techniques.