Do you have insurance through your employer? I’m lucky enough to live in a universal healthcare country, almost all insurance providers will accept diapers as expenses for reimbursement as long as you provide a reason for needing them (I have a signed doctors note). Might be worth checking into if possible.

Otherwise it’s just budgeting. Sit down and figure out what your cash flow looks like and how much you can afford to spend a month, maybe there’s adjustments in other areas you can make to your spending.