i think im pregant AND IM YOUNG idk what to do

hi im a 15 year old girl me and my boy friend of almost 2 years had sex about 3 1/2 to 1 month ago and the condom broke, i was worried so i told my mom and she told me to wait and to see if i got my period. about a week later i got my period a few days early it was pretty much like normal but it only lasted for about 4 days so i thought that was very strange because it regularly lasts about 6 days. i thought i was safe because i got my period. now about 2 or so weeks later im feeling sights of pregnancy suck as dizziness, tiredness, having to use the bathroom more, aches in my lower abdomen, i do fell nausea but its not in the morning its at night around the same time every night. im very confused i think im pregnant but i got my period? or i thought? can u get your period and still be pregnant? i would really like some help i need to know!