Blood test and line progression

I've had a couple early pregnancy miscarriages, and a couple healthy healthy pregnancies, so typically, as soon as I get a positive test, I call the doc and she gets me in for a blood HCG test, and another an couple days later to make sure the pregnancy is headed the right direction. Last night we found out we are expecting again (3w4days- faint line on dollar store test). I was wondering if I still need the blood tests if I just watch the line progression? Would the dollar store cheapies work for this?

With some tweaking: