HCG levels low?

[CardiacRN]

I am 6 days late for my period. I just went off BC last month! I took a hpt clear blue digital reading... said "pregnant!" I could not wait and ended up taking another one that night and it came out negative. I went to the doctor the next day and my urine pregnancy test was negative. Told me it was probably a chemical pregnancy, but drew blood to be sure. well, they called me and my HCG level is 47! Has this happened to anyone else and had a successful full term pregnancy? Re-checking blood levels on Monday to see if they go up. Just hoping this has happened to someone else, trying to stay positive.