What Causes Cramps, No Bleeding And Faint Positive Test Result?

I did pregnancy test on test day, 16 days after EC. Got a faint positive, then did 2 clearblue digital test, 1 first urine the next day. They both said pregnant 1/2 weeks, which apparently means 3/4 weeks pregnant. I am worried as feel it should say 2/3 weeks. Also getting very bad low cramps. No bleeding but am on progesterone injections. Any advice appreciated as my clinic won't do blood tests and haven't got scan for over 2 weeks.
Thank you
Mich