if it's a case of now or never then go for it. If you think if you waited then it would be too late and you wouldn't have one then go for it. But if you could wait a little but longer then I would.
I have a 22 month gap between mine. It's very tiring. #2 was very demanding and unsettled. The first six months are a blur. I feel sad that I haven't been able to enjoy her and spend as much time with her as #1. But it was important to me to have a close age gap for their sake. I'm one of 4 and we are all massively spread out in age because my mum said she wanted to enjoy each of us separately, but my experience is that that has been at the detriment of her children having a close relationship. We were at different age ranges growing up so couldn't play with the same toys, didn't want to play with each other, when one was old enough to enjoy playgrounds the other was too old to be interested etc.
That's just my experience, I know of plenty of people with big gaps and good relationships, I'm not saying any of that to criticise people who have bigger gaps honestly, but it has had a big affect on me and made me want to have a close age gap even though I knew it would be hard. They are currently nearly 10 months and 2yrs 8months and are best friends. They play together all the time and laugh at each other, and B has learnt so much watching her big sister.
So anyway, I'm basically just telling you the pros of having them sooner. There's never a perfect age. If you can afford child care for both, and from what I know of you you seem to have a very supportive H and your son would help, as having extra pairs of hands makes a huge difference. It will be incredibly hard, but if you think it wouldn't be practical for you to wait longer then go for it. Just be prepared for the first 6 months at least to be incredibly hard
Good luck!!