I need reassurance

Ok so I’m going to try to explain this where you can follow along.

I had my first prenatal dr visit today. Going in based on my dates I was 7+3. I’m going based off ovulation. If I went off of my LMP I would be 8+6. Ok....this is where I’m like “wtf is going on?”

They did an ultrasound and baby is only measuring 5+5 but had a strong heartbeat. This doesn’t make sense to me. That is a HUGE difference. Dr did little in reassuring me. All she said was it happens. Remember sperm can live up to 7 days in the right atmosphere. Ok that’s all well and good but I KNOW when I ovulated!! She said she isn’t worried at all. She said we will do a repeat ultrasound in 2 weeks and is took blood today and I go back Friday and again Monday to make sure my numbers are doubling.

Oh and here is another thing...I got a positive pregnancy test on August 9th....nearly a month ago. Based on baby measuring 5+5 than that would have put me at like.....not pregnant lol. It just doesn’t make sense. I’m trying to stay positive. I just need to hear positive stories or positive outcomes. I honestly don’t want to hear “that happened to me and I had a MC”. I’m freaking out and I hate this so much!!