advice anyone?

I got a BFP on Tuesday! I took 3 test as the very first one was very faint. I went to the doctor yesterday morning and did a urine test and she said it was undetermined. I have been having period like cramps for 3 nights now, no bleeding. The doctor ordered me hgc test for the call about it this morning and she said it was low. I'm a little confused about what's going on. Anyone experienced this before? Any possible answers you may have for me?