I say if you want to try, make an appt. with an OB or an RE and discuss all these things. Since you already have a child, I think it may be easier for you to sustain a pregnancy and have a healthy delivery. Plenty of my friends had their first children in their early 40's. There are no guarantees that everything will be perfect, even if you are in your 20's or 30's, so keep that in mind. You can't be sure 100% that you will give birth to a perfect child, but the chances are good.
FYI, I was your age when I tried to conceive my first baby. It hasn't worked out for me and I've been pregnant 4 times and miscarried 4 times, even though my consultation with the geneticist, RE, OB, showed that everything was going along well. So it's kind of the luck of the draw. I have other friends who had no problems giving birth to their first baby at 43 and almost 44.
Think about what you can and can't handle. If you absolutely cannot handle a special needs child, I would say you shouldn't risk it (even though the odds are greatly in your favor that you will give birth to a healthy baby). Life's a risk and a gamble...and that's part of what makes it so wonderful (even when we don't always get our way).
Good luck to you in whatever you decide!
Thank you so much for your response.