PLEASE TAKE THIS TIME TO READ!! Ovulated Early or Late?

I had a period of June 16th-20th apps say im supposed to ovulate on Cycle Day 15 or 16...My periods always last 4/5 days and i bleed heavy or sometimes medium.. My next period came 29 days later..isnt that supposed to be normal?? To count from one period to the next.. This period was July 15th-18th..I was told it was not Implantation Bleeding because my period lasted 4 days and this period was a flow period and medium.. I am very spot on with watching my body as far as knowing pms or pregnancy symptoms or even catching a cold.. If i was already “pregnant” i did not get any symptoms at all..I had sex with my boyfriend after the second period cycle and I notice the changes about 2 weeks after my period ended.. By July 30th my breast were kind of tender but not as bad..By August 1st i logged that I vommitted if anything i gagged as if i did but im not sure if anything came out.. (i dnt remember) By August 3rd i had terrible cramps on the left side of my uterus. August 9th my breast became veryyy tender on the sides.. I knew something was wrong. My next expected period was supposedly according to eve it was August 11th but i never received a period at all. I took a pregnancy test on August 19th and it was positive..But the test lines were dark.. it was a cheap pregnancy test i did not think nothing of it.. I went in for my 8 week sonogram and according to my lmp i was supposed to measure 7 weeks and 5 days but instead I measured 8 weeks and 5 days.. that is 7 days off.. Basically i measured 7 days ahead of my lmp...Is that normal? Does that mean i was only 7 days pregnant before my lmp actually started?? Because it did.. I went online to research why it could have been but someone else online stated that they had a period of June 19th and their expected due date is March 30th but instead they have all the way in April 16 basically the same due date I received..How is it possible she has the same due date as me with no July period but i had a July period and received the same due date as her?? My LMP of July 15th the due date should be April 21st but instead i keep getting due dates of April 14,16,17... Is it possible I conceived before my July LMP??