Want another baby, but spouse doesn't, had 26 week preemie and I'm a vegan!?

My spouse and I have been together for over 4 years, we had a baby boy 3 1/2 years ago, he was born a preemie and spent 4 months in the hospital. He had many complications, breathing tubes, PDA clip, intestine problems, and almost died in the hospital. He is a healthy toddler now with no problems, so I am wanting another baby badly, but I am also scared that I might have another preemie and have to go through the same things. My old OBGYN told me there are drugs I could take so my chances are low on having another preemie, but I do not want to take anything that may harm my body in the long run. The reason I had a preemie is because I had had an abortion (Please don't judge me, I was addicted to cocaine and alcohol at the time) I was completely clean when I got pregnant with my son, and he was planned, so I did everything to have a safe pregnancy. I have been off drugs for over 5 years and I only drink once or twice a year, like one or two drinks max. I'm in a very stable relationship and we own a house together so it's not like I can get up and leave if he doesn't want to give me another child. I dream about having another child and asked my spouse, but he's afraid of having another preemie and what we went through. He is also worried that this is not the right time to bring a child in this world with the whole Obama Socialism stuff going on :( So I'm stuck, I want a sibling for my son and he is against it. I love him and would never leave him over this, so I'm really just looking for your opinions and is it possible to have a healthy pregnancy.There's also another part to this, I have began a Vegan diet as of Feb of this year, so is it safe to be pregnant on a vegan based diet?