Missed Birth Control Shot & Potential Pregnancy: What To Do?

Question
Hello,
I'm 3 weeks behind on taking my birth control shot (Depo). I had unprotected sex with my boyfriend exactly 1 week ago and am currently experiencing "pregnancy symptoms". I've been taking the shot for about 9months now and am wondering if I should be worried about expecting. I've taken 2 pregnancy tests and even done a blood HCG test and all were negative. I also took the Plan B pill on the 5th day after the unprotected incident, as Planned Parenthood explained that it can actually be effective up to 120hrs after. Is it simply too soon to tell or am I in the clear? Thanks!

Answer
I am sorry, but there is no clear cut way to answer your query. I think it is too soon to say especially since you have been using these shots for a good 9 months. Hence The only way to be actually sure is to get a USG scan done in 2-3 weeks time. If you are pregnant it will definitely show in the scan. You can also repeat the HPT in a weeks time to see if it is positive or not.