"Our daughter is 10 months old. She was born with a myriad of birth defects, and her twin died. I'm ready for another baby. My husband isn't. He wants them 2 years apart. I think he's more afraid of having another hellish pregnancy (even though the doctors say the chances of that are the same as for anyone else) than he is of actual said baby. Advice?"
It sounds like you're really thinking about what your husband's motivation is for wanting to wait (being afraid of the pregnancy) but are discounting his concerns about what it would be like to have "actual said baby" (heh) there when your daughter is nine months older than she is. A 10-month-old is a sweet angel of rainbows and light, smart and funny and competent and loving. And you think that this child will always be the same, just more and more mature.
But she won't be.
IME, the months between 18-21 or so are the most turbulent stage for most kids under the age of 3.9 (that's how old my older son is, so that's as far as I know). They can talk, but not as much as they want to. Their thoughts are way ahead of their emotional savvy and language, so they get frustrated and angry and cranky and mean and throw tantrums all the time. They want to do every single thing themselves, but they can't. And they get mad at you if you help them, but they get frustrated when they can't do it on their own. They are extremely jealous of your time, unless you're the parent that they're rejecting that day. Many of them go through a nasty sleep regression (waking up 2-5 times a night. seriously.) that lasts anywhere from a month to three months.
That age is exhausting.
So I don't think you should go into this thinking that "it'll all work out" once you have the baby. I mean, of course it will all work out (and millions of parents have kids 17-21 months apart), but if you do have the option to plan the spacing between your kids, it will be far less stressful on you, your daughter, your husband, and your marriage if you can avoid having a kid in that nightmare stage and a newborn at the same time.
I also think you should take a look at exactly why you want so much to have another baby right now. Why is it so important not to wait another 5 months or longer?
One reason I can think of that might make you want to get pregnant again right now is that you might feel that siblings closer in age will get along better and be better friends. But I don't think there's any truth to that. There are anecdotes either way (my friend who hasn't talked to her 16-months-older sister in years, the kids 18 months apart who spend all their time together, the guy I talked to today who was and is best friends with his brother who is 6 years older than he is, my dad and my uncle who are 5 years apart and have nothing in common). I think what's important is how the parents treat the kids and the expectations they have of behavior. Create the right environment and your kids will get along, no matter how far apart in age they are.
Another reason I can think of that you might want to have another baby right away is to have the chance for a "do over" of your horrible pregnancy, heartbreaking loss, and stressful early days. I don't think there's a thing wrong with wanting a second chance. I hope not, because I certainly did, and the problems I had with my first pregnancy and birth were nothing compared to yours. Consider, though, that you're still pretty raw about the trauma you went through--it hasn't even been a year. And if your next pregnancy isn't the fun pregnancy you hope for, you might be better able to deal with it emotionally if a little more time has passed before you're thrust back into that totally vulnerable place.
(Some other reasons someone might have for wanting to get pregnant right away that I don't think apply to Rachel are that the mother is older and doesn't have much time to have kids, the mother wants to limit the amount of time she spends away from her career, or the couple wants to have many many kids.)
What I'm saying is that I think there's more to it than just "I'm ready for another baby" and "I'm not ready," and you two need to really hash out the pros and cons of having a baby before your first one is at all independent. In my opinion, your life will be a heck of a lot easier if you wait to get pregnant until your daughter is 15-24 months old, but that's just based on looking back at when my son and his playgroup seemed to be mature enough to handle having a younger sibling reasonably well. I'm sure there are going to be commenters saying you should do it now, but just the thought of kids 19 months apart makes me want to take a nap.
Good luck with the TTC. I hope your next pregnancy is completely uneventful and the birth is downright boring.