Why are you going to keep testing until 8 weeks? Please try not to drive yourself crazy. Speaking from experience of a mc in July I know its an anxious time but worrying wont help. Try to remember a line is a line! With this pregnancy (bfp in sept) I did a clearblue digi which said 2-3 weeks when I should have been 3+ and ended up going for a scan the next day due to pain and suspected ectopic and there was a baby with a heartbeat already! I'm now 16 weeks and all going well so just goes to show they can't be completely trusted. I didnt bother testing again after that. Congratulations and try to relax and enjoy it!
I think it is the lack of symptoms that is making it not feel real and I guess seeing a line sort of makes it feel real! I swing from excited to worried. Maybe I should just try and not think about it at all!
Tests have a varying amount of dye in them so you are setting yourself up for a huge amount of stress if you plan to keep testing. You are currently pregnant. Until you get evidence of not being pregnant (significant bleeding and pain), try to believe it. Step away from the tests.