I can't figure out how far along I am!!

Hannah
I can't figure out how far along I am!! My last period was between the 20th and 28th of sept.. I took chlomid and had a vaginal ultrasound the 8th of October. They told me it didn't work like that wanted so as in I'm assuming there were no mature follicules. But I was having intense pain then and a couple days later. On the 18th of October I peed on a ovulation test and it wasn't 100% positive so I'm not sure if I ovulated before or after that. Because I had pains on and off for about a week! But I ended up pregnant and found out last Friday! So I'm not sure how far along I really am! I really wanna know and my first apt is nob 18th someone help!!! But when I pee on a clear blue to figure out how far along it says between 2-3 but the doctors will estimate between 4-5? So what do I do! My obgyn said based on last period around 6 or 7 but hasn't done a ultrasound yet! This is killing me