What other random people have left is irrelevant, there is no norm. Some people don't have enough to cover even their basic expenses adequately while others have thousands a month, and everything in between.
What is relevant to you is that you and your DP should have the same amount of personal spending money after all joint household and DC costs, including saving up for annual and irregular expenses have been covered. She is the child of both of you, so you are both responsible for feeding, clothing and housing her and these costs should come out of the joint pot, not your personal spending money.
Pay all wages and any benefits into one account. Work out how much things like insurance, car servicing, repair and MOT, holidays, Christmas, savings for white goods replacement etc should be and put some in a savings account to cover this.
Pay all bills, grocery shopping, work travel, childcare, DC expenses from the joint account and then split what remains 50/50 between you and DP and that's what's left for your own personal expenses like clothes, food and drink out of the house when it's 'personal' not joint, etc etc.
Things like mobiles and cars can be joint or individual, but if all adults need a car for work, and a basic phone service you could just pay it out of the joint account, but if you want something fancier than the household can afford, you should contribute to the cost out of personal money.
If he won't agree to and co-operate with a system like this, that might be a deal breaker to be honest.