Early pregnancy, just made first appointment

So I found out last week I'm expecting(not first baby) and I made an appt with my ob. I had two blood hcg tests. First one was 17.75 and got retested the second i got back yesterday was 154.40. The lady who scheduled me said I'm a few weeks and scheduled my first ultrasound for sept!!

By lmp I'd be about 6weeks along. Really confused.

I'm 4 months pp and had one period since giving birth to my daughter.(we were avoiding pregnancy) I can't even figure out far along I am and honestly it's driving me crazy.

Any help would be appreciated as to finding out how far I am.

And please no judgement or rude comments. TIA