need-advice-could-i-be-pregnant

I am so confused I am 22 and since April I can’t make head or tails of my period. I have an app on my phone and it is pretty accurate( give or take may be off 3-4 days) So in April I got my period between the 24th-27th and it said I ovulated on the first. My period arrived again on the 15th-18th. Apparently I didn't ovulate again but I did get my period on the 28th-31st. the app said I ovulated on my last day of my period (31st). June the 14th-18th I got my period again and ovulated again on 24th. Period arrived on the 8th-11th of July and it says I ovulated the very next day. The thing is I had unprotected sex on that day and I haven’t got a period since. And going by the app it was due on the 26th-29th of July. This makes me 19 days late! I did have one episode of thick brown discharge two days before my period was due but it was just when I wiped after going to the loo. Never came again. Also my period for Aug was supposed to start yesterday the 13th. What would ye make of that? The thing is I have done 3 home tests one positive and 2 neg. I'm so confused because I honestly don't feel well in myself. I'm constipated which is giving me cramps and A LOT of gas, my boobs are not sore but...''heavy'' is the only way I can’t describe it. I am getting this pressure my pubic line and above my belly button but it’s not PMS. The last two days I have had quite a bit of white discharge but its not the same as discharge I get when i am ovulating. I am sweating a lot more than usual. I'm ALWAYS tired (I could honestly sleep for 14 hrs). But I have now appetite and I not one bit nauseous. Could I be pregnant? Any insight would be great but please no smart comment. 

Thanks!