22 Days Late

I have a regular cycle that usually are 28CD.

My last period was January 11. I have taken hpt's and they are all negative, I went to my ob and she gave me a hcg tumor blood test. From what I have read this is to determine a germ cell tumor. Could this also work to determine pregnancy?

I have many symptoms: nausea, headaches, backaches, tender breasts which are firm and have grown about a full cup size.

All in all I feel pregnant. I have been pregnant before and didn't receive a postive until about 8.5 weeks but right now my Dr wants me to start progestin, and I'm a little worried to take it just in case I am.

What should I do?