PLEASE answer this if u KNOW and especially if have gone through something like this?

So my periods have never came at an exact day of the month every month so I really don't know when I ovulate my cycle is all over the place.. I always went off the whole 14 days in cycle so about 2 weeks after my period I umed I would b ovulating. But now that I see alot of women saying that they have gotten pregnant having even a day after their period I'm freaking out cus that's my case.. I ended my period the 12th of last month and had unprotected the 13th few days after I was NOT feeling good... I keep burping and feeling super gy I never ever feel sick and sometimes throw up a little in my mouth.. started cramping as if my period is coming but now I don't even know it's ridiculous how much I burp and let out gas and go to the restroom for both number 1 & 2 most days I'm constipated tho I keep getting heart burn and even this feeling of "stomach burn" I guess I'm experiencing acid refluxes.. The reason I think I might be one to ovulate at an odd time is because the only other time I had unprotected was exactly when I "thought" I'd be ovulating an I didn't get pregnant!! && it was perfect timing!! So it's the 10th today and I took already three hpt's few days apart from eachother && it came out negative! But I have ALL symptoms & find it strange that they came so early on How long did u wait till u finally got a positive! && i can technically be considered late but like I said my periods aren't exact every month so it can come any time now..