Hi L.. I have a 6 month old girl, my first, and I'm soon to be 42. I didn't get married until 37, my husband and I tried for over 3 years, and finally got pregnant with IVF. So, I didn't have much choice in when I tried. I will say there are pros and cons.
First off, no one ever gives me looks or anything like that, because it's so much more common these days. You're right, there is a greater risk of downs, although the chances are still low. After the initial screenings, our chances of miscarriage from amnio were greater than chance of downs, so we didn't do it. I really think you just need to be at peace before you get pregnant that there would be a higher chance of downs, and although you can't know until the time, you can have an idea of what tests you'd run with risks involved, if you'd follow through with the pregnancy if you found out early it had downs, and be on the same page as your husband.
I had some complications too, although not as severe as you. I was on bedrest from month 5 and on for premature contractions, and I delivered at 35 weeks.
The good things about having a baby now are, you are more mature and know what you want and don't want, and you've seen more parents do things that you would or wouldn't approve of. Also, your older daughter can help out! And of course, you are usually a little more financially stable, if not savvy.
The bad things are that you will be older when the baby is a teen, but if you're young at heart, I wouldn't worry about it. Plus, he/she will have a big sister to help them out. I'm exhausted, like drowsy exhausted and physically exhausted all the time, and I always thought that was normal, but now I'm guessing it doesn't help that I'm older (plus I work 30 hours a week). Still, I keep up with my daughter, and so does my husband who is 2 years older than me. One big con for me is that I've had an impossible time losing the baby weight, and I think that's MUCH harder when you get older, unless you're well off and can afford someone to watch the baby when you work out.
But, the bottom line, it's a great joy at this age too. If you want to try, I think you should because you may regret not doing it in a few years.
Do remember though, it's much harder to get pregnant as you get older, so it may not be that easy. Good luck and follow your heart.