your mom could say it to see your reaction so she can determine whether you are having sex or not. the doctor cannot determine, "YES, she has been having sexual intercourse and thus not a virgin" but he CAN take a look at your hymen to see if it has been broken, and if so, how much of it is broken to determine that you either had broken it by: strenuous activity like horse back ridding, or sexual intercourse (or some activity involving object(s) penetration), or giving birth to a child etc. so that would mean you need some type of excuse for your mother. could she be joking? of course! a lot of states in america have a "protection" for minors who are sexually active--they keep their visits and information confidential unless life-threatening or rape and such. this helps minors who ARE sexually active feel "safer" and thus are willing to go to clinics and doctor offices to get checked up and learn more about intercourse and its consequences to prevent unwanted unplanned pregnancies/STD's/rape etc etc.
but now for my opinion! :) you're 15 years old, you're not old enough to have sex. you can't even watch a rated R film yet, nor can you buy a slingshot in the state of Washington. that most definitely shows that you're not old enough for sex (well, of course you ARE technically because you're supposedly "physically" ready) another factor that makes me believe you're not old enough is the fact that you can't even spell properly or use the right spelling for the word you're looking for. here are a few examples:
pregnance = pregnancy (could've been a typo, but the 'e' and 'y' are actually somewhat far apart on the keyboard)
yestarday = yesterday
weather = whether
and this doesn't include the typos or common short-hand typings like:
abt = about
were = we're
goning = going
though = thought
... etc etc. im sure you know what i mean.
another thought. being together for "like 3 years" when you're 15 means "dating" since you were 12. i'm sorry but, when were 12-year-old datings ever mature enough to be called "relationships?"
next thought--protection isnt always 99%, even if used properly. there are many many forms of 'protection' and very few actually HAVE that 99% effectivity. it'd be nice if it was! but it isn't.
i'm not going to tell you to stop having sex because it's not my place--just my 2 cents :)