Havent had my period for two months, took pregnancy test twice both was positive. however my gp cant see anything on the scan its been 2months, why?

Ultrasound: Get both a qualitative and quantirative HCG blood bregnancy test and a transvaginal ultrasound from your OB-GYN.

No IUP: hmmm, are you having pain? The pregnancy could be outside the uterus or ectopic and I am sure that he is concerned about that. Molar pregnancy is possible. This is an uncommon problem so you need to hang in there for your doctor to work it out. i am sure that he is doing serial quantitative HCG and working with colleagues to try and figure it out.