anxiety

I think I may be miscarrying. I have been bleeding for three weeks. the first week it was light and then the next week it was heavy and there was tissue or whatever you'd like to call it in the toilet after I went pee and now I have stopped bleeding as much but still am bleeding. I have wanted a baby for a long time and I'm scared. I can't stop over thinking and I was wondering if anyone had a similar experience or had any advice or anything. Its taking a lot no to have a panic Attack right now.