Please read :) topic is negative and positive pregnancy tests!

AF is 31 days late and I had four faint positive home pregnancy tests but two negative blood tests? My dr said if I get any bad cramps go straight to the ER but he won't tell me why or what he thinks is going on? Does anyone have any ideas?? I understand that no one can give me exactly what's going on unless you're a dr or something but if anyone has any thoughts on what's going on please tell me I'm super worried! 

Ps my boyfriend and I had unprotected sex (we are ttc) in early or mid March. Also I have had cramps (not to serious) and bloating, breast tenderness and fatigue. If any of this information helps. Also if anyone says about an ultrasound he's making me wait a week before getting one :) 

I appreciate any thoughts or ideas!