Went from 8 weeks to 5 weeks?

Last week I had my first doctors appointment, which according to my last period date (April 22nd), the doctor estimated approximately 8 weeks!

Now, yesterday, for my first ultra sound the size of the baby only indicated 5 weeks. No heartbeat (yet) and too small to tell really anything. He said blood work also indicates more around 5 weeks.

Doctor didn’t seem too enthusiastic or overly concerned overall... but wants me back in two weeks for a follow up.

I’m thinking maybe my time of ovulation was off because I had only recently been off birth control (January), and maybe that mixed things up a bit.

Anyone have any similar situations like this?

Guess my husband and I were excited about being able to kinda see what’s going on and maybe hear a heartbeat and now it’s too small to tell. Just hoping everything will be ok.