Really doubting I'm indeed pregnant

About 2 and a half weeks ago I had spotting for 3 days something I've never had before. I was still 10 days from my period being due. Of course my first thought was could this be implantation? But I've had my tubes cut, tied, and burned for 6 years. I've had 2 chemicals since then. Well my period came due. I'm currently 8 days late. I've taken so many tests with mixed results. At first I was getting faint lines which gave me hope that maybe it was a miracle. Then Monday I got the darkest positive yet. I see the obgyn Wednesday. So I've been testing to make sure my levels were going up. Instead they've been fading and tonight nothing at all. I have all the symptoms of pregnancy I had before with my kids but I have a feeling come Wednesday I'll be told either it was another chemical or it's ectopic and not going to be viable. What honestly are the odds I am indeed pregnant? Wednesday they said I'll get a urine and blood test as well as an ultrasound. It's just been eating at me and time isn't going fast enough. Thanks for listening to my ramble. Any positive advice is appreciated! I want to be hopeful this could be a miracle but I'm pretty dang sure this isn't real. Even if it's ectopic at least my bf and I know I can get pregnant again. The only reason I got sterilized was because of my ex husband I refused to have anymore kids with him. My bf and I have had a wonderful relationship for almost 4 yrs. We would love to add a little one of our own to our kids.