Was this a miscarriage?

I'll try to make this quick and limit the tmi ;). A few weeks ago I thought I had a miscarriage. The midwife said that it would have been between 5 and 6 weeks.

Reasons I thought I was pregnant:

1.I'm trying to get pregnant

2. I took two tests and both were positive - one 4 days after my missed period, and one 6 days after.

3. Tender/painful breasts starting a couple days before my missed period and increasing in pain until miscarriage.

4. Weird, heavy, uncomfortable feeling in my abdomen until miscarriage.

5. A few bouts of slight nausea...nowhere near actually throwing up

6. Very tired, needing a nap everyday.

7. Peeing all the time

When I had what I assume is a miscarriage, there was a little bleeding and then a couple hours of horrible pain. For the next two days I did not bleed much. It was a Saturday and Sunday, so I couldn't see my doctor. I passed a little blood, but mostly little pieces of stuff...it looked like someone popped a thick black balloon.

I went to my doctor on Monday morning and she felt around on my stomach and sent me to get bloodwork and an ultrasound. By the time I got to the ultrasound I was bleeding a lot. My assumption is that the doctor feeling about got things moving that were stuck. There was a lot of blood and also some matter in the toilet. I never passed more than a couple of blood clots. I did pass a weird dull brown blob a day or so after I passed a lot of blood.

The problem is my hcg levels were basically zero. So that would mean that I was never pregnant at all. I don't understand how I could have all these symptoms and get two positives tests. One of the tests was a First Response, I forget the other one. They were both made to detect pregnancy early. Although I got the positive lines...the lines were pretty light. On the second test, I thought the line wasn't going to show up...but it did right at the end of the three minutes.

Is it possible that I was pregnant, but that my body wasn't making enough hcg? Does this sound like a miscarriage...or just a late/bad period? I'm going to see a fertility specialist next week....If my problem is that I don't produce enough hcg, that can be treated....right?

Thanks for your help :)

(Advice from people with experience rather than just opinion is really appreciated.)