Oh Gosh you are not certifiable for sure; it's absolutely normal to want another baby, how can we not? Honestly, in my opinion there's nothing else in this life that brings as much joy as a baby. Just watching them grow and interact with their siblings, it makes everything worthwhile.
I've never heard anyone saying they regret how many kids they have, if anything I've heard older adults saying they regret not having more (not everyone but I know many who think so).
Having said that I'll recommend you to have a talk with your doctor about possible risks and your overall health. If your OB gives you the go, then have a serious talk with your husband, without fighting or being pushy; just ask him the reasons why he does not want another child. Also offer solutions, if it's money tell him you are willing to make a budget and stick to it! if it's the night feedings, tell him you'll handle those and really mean it. Don't just say it to make him agree and then expect him to work 60+ hours and then help around the house. Show him that you can handle three children, make a commitment and make it work, maybe he is worried about finances and the extra work; I'm positive he will love the baby as soon as it arrives.
also, make your health a priority before trying to get pregnant, really be in your BEST shape so you can nourish your baby and hopefully have an easier pregnancy.
If after a heart to heart talk he doesn't want to have another child then I think you should leave it to fate/God and really make your peace with having your two wonderful children.
I always wanted to have 4 children, I have two, I talked to my husband about another and he said no. After he saw how happy I am staying home, playing games with my girls and just enjoying them he decided not to get a vasectomy (which I had initially asked him to do but changed my mind, what was I thinking!). I wasn't putting an act, I really made an effort to keep the house clean and not slack, it turns out it became a routine and it's easy now. I cook 4 days out of 7, the girls are happy and I'm planning to homeschool both of them starting next year (3rd grade and preschool). Not everything is perfect but we've learned to let go of "perfect", if another baby comes (my youngest is 1 like yours I want to start trying when she turns 2 next year) the house won't be perfect but we will have each other, I can't wait for my family of 5.
By the way can you believe that 3 children are considered a lot nowadays! my mom is the youngest girl from 11 siblings! It's a shame that some people look down upon big families, if a couple can afford it why not? children are a blessing,
Good luck to you and have a great long weekend!