Period late 2 months in a row...

Soooooooooo I had sex roughly 2 months ago, 2 weeks before my period (yes we used a condom) but we didn't finish. And that was the first time I had sex in many many many months, so I believe it threw my period out of wack before it skipped for a month just like it did the first time I had sex.

I took 2 pregnancy test and they came back negative. Then a week later I had my period(whole month later after I should've had it). The week after that I had went on a week long trip and was walking nearly 20k steps a day, I normally walk between 6-8k (I know... I'm lazy) so currently im 3 days late and I think I'm just now ovulating.

I took an additional pregnancy test and it also came back negative...

I even did some research and read up on implantation bleeding however they said it only last between 3-72 hours and is consistent and there's no clots, but during my what I believe was my period wasn't a consistent red color and had a lot of clots... like normal and lasted 5 days.

My period is very irregular and is typically 31-33 days if it doesn't skip, and yes my period skips at least 2-4 times a year. Yes I've been wanting to take birth control to fix it however my mother would never let me get it during my time in school because she didn't want me getting sexually active.

I think from me extensively walking and being paranoid and suddenly losing 6lbs in a week is causing my cycle to get all wacky. I want to go see a doctor but I don't want to end up wasting money and being told it's because I'm stressing so calm tf down. Plus im kinda scared...