Hi hun the pregnancy/birth success rate these days with the technology and medicines they have I'm sure your birth will be straightforward as the others! And if not, it could very well be nothing to do with your age! I had my two at 21 and 23, my first birth was textbook, and my 2nd was horrendous, ended up losing so much blood and almost needing a transfusion luckily they stopped it in time, my placenta started tearing away into pieces inside before it had chance to come out, resulted in me having a serious infection with a temp of 41, if they didn't bring the temp down or stop the bleeding when they did, I dont really know if I'd be here today, my body almost shut down.
BUT they did, and me and my son were great and came home 3 days later
Anxiety is a horrible thing, and like you I worry about the birth of this baby just incase a similar or worse thing happen. It's not age related that makes pregnancy worse or makes your luck run out, it is literally just chance I believe.
You'll be okay hun, easier said than done, but relax