I think I may be 3 months

I graduated in may an me and my boyfriend went on a trip, we had sex the entire trip and on two different nights the condom broke. I've been on the pill since I was 14 but in December I had to go off of it for a month for surgery and I haven't taken it on schedule since then, I take the pills when I remember I also was on antibiotics at the end on April and our trip was on the 13fh of may. I haven't thought anything about it may I had a 3 day period not too heavy, my normal periods are at least 8 days long. 2 weeks later I had a 3 day period that was brownish then 4 days went by then anoth brown period for 3 days then another one at the last week of June. July no period. I had a two day light pinkish and brown period on may 4. I've been on the pill this entire time. I've been constantly nauseous and my coworker asked me If I was pregnant, I laughed but he was like no I'm serious ur always nauseous and your back always hurts and my best friend chimed in and said yea and that I've been going to bed at 9 and get up at 8 and I'm still tired I pee all the time and they also think I've put on a couple of pounds but I've been working out and dieting. I think theres a chance I could be pregnant but I don't know why I would still be having periods unless it was because of the pill. Please send me a serious response, I plan on getting a pregnancy test in the next couple of days when I go grocery shopping