Miscarriage or never pregnant?

I'm posting this to try to get some answers.I'm really confused right now.
My period was over a week late,so I took a pregnancy test.It was positive,so I took two more just to be sure.They were both also positive and different brands.Judging by my conception date,it would have made me 5 weeks pregnant.

Sunday I noticed some spotting that was light and didn't think anything of it.
It continued most of this week.Today I started having really heavy,bright red blood that was mucus like and had some clots.I didn't really have much pain but did have some mild cramps.
Tonight I took another pregnancy test,and now it says negative! I don't know what to think.If I did just have a miscarriage,how could my pregnancy hormone levels already be down enough to give a negative test??
Is it possible 3 tests were wrong and I was never pregnant at all?
Or is it more likely that I had a miscarriage,even though it was rather mild?

I have an appointment for Saturday at the doctors to figure out what is going on,but I'm just trying to wrap my head around it all.
I definitely had pregnancy symptoms too: Hair and nails growing faster,nausea,fatigue,emotional,big boobs and tummy did seem bigger too.
I was also peeing a lot.

It wasn't a planned pregnancy,so I guess I will be relieved if I'm not.But I'm also a little sad too.I didn't even have enough time to go to a doctor yet or think about it much.

Any ideas?