I'm scared and confused...is my hcg level too low?

Mommyslovebugs

My home test came back pos., so I went to the doc last Tues.  Their urine test came back pos.  I told my doc that my last period was July 15th.  He said I was prob 4.5 weeks pregnant and then I had my blood drawn to check my levels.

 He called me the next day saying my hcg level was only 188 and I had to be only 2 weeks preggers.  I thought you added two weeks (even though you're technically not preg, but they always add two weeks right?!!?).  I asked him this and he said I was confusing myself.  But, if I were only two weeks preg, technically I became preg that day??? What about the freaking two weeks they always tell you to add?  Am I not really four weeks preg.  And if so, are my levels too low?  I have an appt to redraw tomorrow to see if the levels doubled enough or if it's not a successful preg.  I've been so stresshe and confused his past week. What should my levels be if my last period was July 15?  My cycle is every 25 to 26 days.