Medical expenses: This varies, especially by insurance. Insurance is very picky and, as I’m sure you know, things have to be coded properly to be covered and sometimes you can have a technically covered procedure be not covered because it was done a different way (for example, if your doctor just ran a lab without getting permission from the insurance, or if your insurance wanted you to see a specialist instead) so this can be a big one, or it can be minimal.
Diapers/wipes/formula/whatever: Diapers/wipes can be a minimal cost if you shop smart. Big box stores often have deals that if you buy X, you get money back, a gift card, or free items, so it’s best to look for those early on, or before you have a baby. Warehouse stores offer great deals, too. You buy in bulk, you get a nice price cut. Cloth is also an option.
Furniture for baby: Stupidly expensive. Just.. it is. You can minimize this by using things you already have or second hand (re: cribs — definitely don’t get a crib older than 10 or so years. Many of them have been recalled.)
Daycare: Another variable but based on your situation, this will probably be the most expensive outside of medical bills. Daycare is just.. stupendously expensive.
My situation was that I’m on Tricare, and my prenatal and postnatal care was covered 100%. Our initial costs were to purchase necessities for the baby, such as the furniture for her room (which was around 2-3000 give or take to furnish an entire room) of which we _did_ have help from our parents, so it was less of a strike directly on us. Formula was a non-issue for 8 months as I breastfed as long as I could, and my mother gifted us cloth diapers, so diapers were a non-issue outside of getting past the “oh god this is so gross is my baby leaking demon blood” for the newborn phase. Lords help me.
Then you just end up with small things you don’t really think of that add up quickly: Nipple shields (expensive, like 10/ea), lanolin, baby lotion, changing pads, receiving blankets, disenfectant, baby soap, baby tub, tub toys, etc etc etc.
Raising a kid isn’t cheap.