Looks like a nice tight ship! However, there are a few budget items I'm not seeing:
- Property taxes & homeowner insurance - for your mortgage balance, unless you have a crazy low interest rate, it doesn't seem likely that these are included in the mortgage interest/escrow figure.
- Home repair, car replacement etc - these are long-term but knowable expenses and should be budgeted
- Vacation spending
- 529s for kids - I assume you'd like to put them through college?
- HSA, if applicable - look into this as you're at the ideal age to take full advantage of this
- Emergency fund - with 3 kids you should definitely have one. 3 month expenses at minimum.
Good luck with your FIRE plan!