evap question

SO. I suck at producing HCG early on. I was 11 weeks when I found out with my second son and the Dr was convinced by my test I was 5 to 6 weeks because it was still faint. I had to have a ultrasound to convince her otherwise (no idea I was pregnant just a decent guess based on intercourse). which leads to my question. will every test have an evap line?! I have 8 tests from the last week that I'm driving myself nuts over evap or faint positive, gray or color. surely not every single test would have an evap? I mean faint line in the timeframe that darkens some over time, defiently is there initially not a negative that gets a line hours later. any input?