Losing hope....

I'm 26 yrs old, and have had 4 miscarriages. Two when I was 18, and two since I turned 26. My last two were truly devastating. I got married 3 yrs ago, and we waited a year before we decided to try for a little one of our own( he has one from a previous marriage), it took almost 1 and a half to come up pregnant. We lost it just a week after finding out. I was told it was only chemical. Well, we didn't have to wait long before we got another positive test. I was over the moon with joy. I tried to do everything right. Took my prenatal vitamins, slacked off on soda, slowed down and almost quit my smoking, and everything. When it came time for my first ultrasound, me and my husband were excited, but they told us the couldn't find the fetus. My heart dropped. But the doctor said we might have guessed wrong on how far along I was. So we waited 3 more weeks, went back in and still couldn't find the baby. My levels were rising and everything. Unfortunately, Halloween night I was rushed to the ER with severe pains. I was told that night that I was going to lose my baby. I was crushed. I made an appointment with my ob-gyn the next day. Unfortunately it was too late. I lost my little bundle on Nov.1,2018. And they can't even tell me why. It's been almost three months and I still don't feel any better. I feel like it's not worth it to keep trying. Like no matter what, I'll never get to have a baby of my own. I've struggled for almost 2 yrs trying to conceive, and doctors can't tell me what's wrong. I just feel lost.....