Hi Brooke
Your life certainly has changed drastically -- that's a lot to take on in one fell swoop! You must be utterly exhausted, so I'm not surprised that you're having some difficulty finding a solution.
Most people have the opportunity to adjust sequentially to being a couple and having each child. You and your fiance have taken a quantum leap to a place where you're having to deal with the emotional challenges of figuring out who you are as a couple at the same time as you are dealing with the exhaustion of new baby and the physical demands of a toddler. Please, please don't think that is something that you should be able to just take into stride! You have a wonderful new family full of love, and you are both going to have to call upon every single coping mechanism you have ever learned as well as some new ones in order to make this huge adjustment with your sanity intact.
It hasn't been socially acceptable for women to be expected to automatically take the role of housekeeper and cook for some years now. Many men are hopeful, and some still expect but that's their issue, not ours. Consider how you and your fiance would have divided these things up if you'd had the chance to be a couple first, with both of you working outside of the house, and don't let yourself fall into thinking that looking after your baby and toddler isn't a full-time job equally, if not more, important as his. If you're concerned about the financial contribution that you believe you're not making, do the math.
A piece of wisdom that I've picked up along the way: "Start as you mean to continue". If you're happy to forever shoulder the elephant's share of the work in your family, then do so and be happy. If that's not what you want, but it's what you're doing, what you're also doing is sending mixed messages to your fiance. He loves you and wants you to be happy, so talk to him and work out a better balance -- you'll all be happier for it.
You've heard this, but repeat it to yourself every day, every difficult moment: you will get your neat and organized home back -- looking forward, it may seem to be ages away, but looking back, it will feel too short -- and you will never, ever regret this time.
Be kind to yourself :)