Help me please. All options are helpful and needed.

Ok so my last period was July 26,2018, I’m 2 days late every month and my period is 7 days long , they’re always normal. Well I missed the whole month of August, but I get my periods every month so I tested the whole month of August and they were all negative then in September I had sex on the 2nd, & then on the 14th I tested positive for pregnancy, i went to the doctor and no fetal pole was found, or yolk sac but my hcg levels are rising because on a Tuesday I was 378 then on Saturday it was 1418. So how do I find out how far along I am? Due to my LMP I had thought I was 8 weeks but turns out I’m not. I’m earlier than that.