Horrible Periods

I started my period when I was 13 or 14, the typical age to start a period (I honestly can't remember exactly how old I was when I first started but...yeah). Since that time, I've experienced some pretty bad periods. Mine last for between 5 to 7 to sometimes even 8 days long and the cramps sometimes can be so bad that I'm doubled over in severe pain and feel like puking. Not to mention I have such a heavy flow (I use size super in tampons (just makes me feel super, right? Eh....thinking not)). My mom says that endometriosis runs in her side of the family (one of my aunts has it I believe) and so do ovarian cysts.

It just makes me wonder if I have either of those things going on with me. Still need to go to the gyno for the first time to be examined and stuff. Should've went a long time ago when I first started having sex (back in........June of last year). My boyfriend and I have sex without there are children here!s and he pulls out right before his big moment (we're both serious about each other, kind of going through an odd phase right now but it works for us; we aren't dating but we love each other very deeply.....confusing, I know). We've talked about possibly having kids some day if we get married (which get married is looking very likely). I'm afraid I won't be able to have kids :( I was pretty certain some girls could get pregnant through the pre-cum and I heard there was a girl just fooling around with a guy, no penetration, still a virgin and ended up getting pregnant from his pre-cum. *sigh* Just nervous, worried and scared all at the same time.

Anyone mind cooling down my nerves a little bit? And maybe telling me I'm not the only one in a situation like this? Thank's so dearly to anyone who helps me out :)