Pregnant?

Okay. So ever since i started my very first period. Its never been regular, maybe 4 months at a time. Ive even gone 6 months without a period or sex... Well me and my boyfriend of 4 years are not necessarily "trying" to have kid. But if we do itd be a blessing. Since feb 12 weve had sex about 5-6 times and everytime he has came in me(deep). A couple of days ago i got two huge pimples. Witch usually happens right before my period. Well this morning i woke up with very tender nipples. That happens to when im about to start my period. But With the sex weve been having. I Think i may be pregnant. I need some advice really bad guys....