First off, I am sorry for your loss *hugs* I've heard too that your 1st AF after m/c is supposed to be super heavy. I just started mine yesterday, and it's only a bit heavier than my usual. (I had a d&c, but 11 days later I was bleeding heavy and passing huge clots so I had to go to the ER...sorry tmi...they said they prolly hadn't gotten it all and I passed the rest on my own)
Maybe this AF will pick up in intensity...mine sometimes starts off slow. Or it could be b/c you lost so much blood with the m/c. I wouldn't worry too much. I would be worried much more if the bleeding was super heavy. Light flow is always better in my book!

If you get worried, of course call the doc, but I think you're just fine!