Bleeding/spotting for daaaayyyssss ...

Karen
I have PCOS and only ovulate about 4 times per year. I'm currently being treated withr Metformin and Clomid. This cycle, however, I didn't ovulate prior to CD 29 (I stopped checking because I was wasting test strips and I went on vacation). 
On CD 39 I started spotting which has continued (varying from light-moderate black like blood to bright red with clots) for 3 weeks. It slowed down to almost nothing on CD 52 that DH and I BD
Because I'm still spotting I had a pelvic exam and blood work done but nothing out of the usual (at least for me). Today I had an ultrasound and my spotting had slowed to light brown spotting (more discharge than blood) and I noticed some very mild cramps. The doc who did the ultrasound said I had a GREAT uterine lining that was perfect for implantation and that she wouldn't be surprised if I was pregnant. She's fully aware of all my symptoms so far but she insisted on a urine pregnancy test and that I should take another in a week if it's negative. 
Up until that point it didn't even cross my mind that I may be pregnant, especially since we've been trying for over 9 months and nothing. Buuuuut we did BD 7 days ago, my spotting and cramping today is consistent with implantation bleeding. There's no point in testing again for a few weeks, but is it possible to spot/bleed that much and have successful implantation? I just REALLY don't want to get my hopes up. 
Has anyone else had anything similar and they WERE pregnant? 
Thanks!