Late period???

So I used to have an irregular period. But after I turned 18 and gave up my virginity, they've become regular. At first I was in horrible pain when the regularity began. It's been almost a year and it has subsided. But based on my tracker and my mental calculations, I'm late one week. I've been eating crazy shit stuff, overeating, been constipated, back pain, fatigue, and dehydrated. No period for about 5 weeks. We last had sex the Monday or Tuesday after Valentine's day but we used condoms. I don't think any of the condoms broke because I was right there so I doubt I'm pregnant. Any idea what's happening?