Vvfl .. 2 days late. Got a faint line yesterday and this morning its a lil darker than yesterday..

Basically I'm asking...when will my levels go up so I can see a definite line? I'm not believing I'm pregnant until I go in but I'm not yet cause well the tests are barely picking it up..I had a tubal last Feb and my due date now...is the same it was for the baby I lost last year. I'm just so nervous...but mostly scared. I'm happy too...trust me. Just don't want to lose this one..I only have one tube left as well. Thanks.