I'm sorry for your loss. When I lost my baby at 12 weeks 4 days, I couldn't think about anything else other than being pregnant again. It's devastating. The hormones don't help. I had to take a break from the pain for a bit, so I went back on the pill for a month to let my body and mind recover a bit. It really helped settle my hormones out.
Your husband might be right, and he might be adamant that he's too old, and you might need to accept that your family is complete.
On the other hand, he might be grieving and not able to even dare to hope, knowing that it would be distressing to you to go through this again.
Why not take a month to consider carefully. Look at your life now and weigh up the pros and cons. My daughter is currently 13 months old and sleeping in my arms (because I can't get her back in the cot after a bad dream). I have the cold, I need to pee, and my cuppa tea is going cold.
I wouldn't have it any other way, but are you ready for a mini tornado to sweep through your family? I have fanciful thoughts about a football team, but it's not practical financially or health wise. I'm lucky to be here, I don't need more.
I'm not much help. I hope someone more useful comes along! Keep talking to your husband and grieve together, don't pull apart. It's a horrible time 