I need help !!!

Nakita • Sun, Nov 30 • 30 years old, Married Baby 1- June 2015, Baby 2- October 2016, Baby 3- March 2018! Baby 4 October 2019

I am 12 weeks pregnant an hvent had any symptoms the whole three moths .. I have been to the doctors a few times , saw baby an heart eat at 7 weeks but I decided to take another test for reassurance. The line was there but barely !!! Can this have anything to do with how far I am , has this happened to anyone else ?