heartbeat at 6 weeks

I went for an US on Wednesday. They said it looked good, some small implantation bleeding. I got to see babies heartbeat :) my doctors nurse initially told me it was hopeless because my progesterone was 4.4 at 5 weeks. But we are proving them wrong! How early did you wear maternity pants? Someone gave me maternity pj pants and they are so comfortable! My belly is so tender and bloated!