Not enjoying pregnancy

Okay, so the only dream I’ve ever had in my whole life was to be a mom. This is all I’ve ever wanted. I got married, and after over a year of trying to get pregnant, I finally got a positive pregnancy test on Christmas eve. I was over the moon with happiness. I had a box of cheap pregnancy test strips so I decided to do progress tests and watch the lines get darker every 2 days to use them up. The line got darker, and then faded to almost completely negative after a week. I panicked and called my doctor and went in to have my blood drawn. They said I was pregnant and my progesterone wasn’t really low, but they put me on progesterone just in case. Then I spotted with stringy brown and red discharge for a week. I panicked about that too. My doctor said it was just implantation bleeding that just lasted a while. At 6 and a half weeks they had us come in for an ultrasound and they said there was no baby, no fetal pole, no yolk sac. And that I need to come in in 6 days and talk about options and if I start to miscarry before then to call them. She said it was nothing I did wrong. She sounded so sure it was over. I was devastated. I couldn’t do anything for those 6 days because I was so heartbroken. We came in 6 days later and there baby was with a heartbeat and everything. She was so shocked and so were we. Measuring exactly to the day I knew we conceived because it is the only day we dtd and the day after I got a positive ovulation test. I knew exactly how far along I was to the day, so I knew if they saw nothing that they must’ve been right. But they were wrong. I’m so grateful for our miracle. But now I am almost 15 weeks pregnant, and I still feel terrified every day. I can’t talk to anyone about it because they will think I am being ridiculous. I have been given a blessing, yet I am spending every day waiting to lose my baby. I’m scared every day that I will lose this baby, and I can’t enjoy it at all. I started having terrible panic attacks where I hyperventilate and cannot catch my breath or calm down because I am so stressed. My doctor wants to put me on antidepressants, but I have been put on the exact same ones before and they did not go well. I don’t want to put any stress on my baby, but I can’t seem to relax and enjoy this pregnancy. My first baby, and I’m miserable and sad. Is there anything that anyone can say to ease my worries?