Due date conflicts

So when I used my period and date of conception (I was tracking and knew my dates) it had my due date at Aug 5th-6th.

I do not have insurance and do not qualify for Medicaid so it took a while to get in somewhere. I used private ultrasound places earlier on to confirm heartbeat etc. They do not date you but just from experience baby looked right for those due dates I had.

Fast forward to finally having a doctor he feels my belly ans checks with doppler and can't find heartbeat at 13weeks. (Im a heavier girl atm) he says "oh maybe you're not as far as you thought".. I said I know my dates.. and he says the same. He has a scan done when I should have been by my dates 14 weeks. Baby measured they said at 15.3 giving me a July 27th due date. So he moved my due date to then and I said but I know when I had sex etc and it was only one time. He said maybe I was wrong etc. But it was literally once in a two week span and a date of July 27th would but me right on my period to conceive and I know I didn't have sex till much after. He annoyed me acting like I was wrong.. but no other doctors around to see.

Then a trip to the E.R. for dehydration and they ultrasound and say baby's on the date for what I orginally had.. so I know it isn't a big deal it just bugs me sometimes.

I feel like baby is just big and I know I should be around August 5th not July. Maybe it stays on my mind because all my pregnancies I develop pre-eclampsia and need to be induced and worry a out baby being more behind than the doctor has me at. So jm frustrated he went from saying I was wrong and not far along to oh now I'm 10 days ahead? Also all my babies have been 8.12 or more but none measured ahead.

I should be 20 weeks tomorrow and still barely feel any movement. For me that is odd as I already felt much more by this time with my others. Granted I'm a bit heavier this time.

Anyone had this? Just a vent I suppose but ugh. I wish there was another doctor but there isn't.

Edit to add: my last period was Nov 1st. I had sex that day in the am. Period came that night for 5 days. I never had sex again until the 12th. My cycle is normally 26 days. Fertile window was the 11th-16th.

Again only on my mind because two dating ultrasounds had two different dates. Dr had July 27th er had August 5th like I had.