How to deal with the anxiety and uncertainty

I have a beautiful 5 year old son, but I've had 3 losses since he was born, all in the first trimester. I had all of those losses with my ex husband. I've been with my new partner for over a year now, and I just found out I am pregnant a couple of weeks ago. Today I'm 5w2d and my HCG is doubling great, but it always does. My progesterone is fine, but I've been lightly spotting for 13 days now. I have so much anxiety over this, and I haven't let myself get excited at all. This is my partners first pregnancy, and I feel like I'm depriving him of excitement and being a Debbie downer. I am just so guarded and don't know how to relax about this. The docs say everything is fine. I don't have my ultrasound for 2 more weeks, at 7w2d. I'm losing my mind, and afraid that there will be no heartbeat. How can I get through these 2 weeks without worrying 24/7 and if this pregnancy does work out, I'm not sure I'll ever accept it until a baby is in my arms. I just had to say it out old someplace.