Really worried!

Tabatha • I`m married to my high school sweetheart. We have two beautiful daughters.
Okay, so my period was suppose to come April 20th! I haven't seen her yet! I've been testing since that day. My lines haven't gotten darker yet. I've been getting super faint lines!! I'd be around 6 weeks right now. I can't get a blood test til next Friday, May 12. Can anyone give me some advice on what it could be? Something I could research? I'm just going crazy, because I have neverrrrr been 15 days late before! I can attach hpt results if needed! Any advice is appreciated!