you guys need to sit down and see it as a combined household income and work out what needs to go to where. it's not about who earns the most in the family and who earns lesser. If this was the case you should have put this as a criteria before you get married or check her background so that you are marrying a partner your same level.

The fact that you have a kid with her says that the above is not really an issue for you so just sit down and write down all income streams and agree on these are the funds going to these different expenses.

Work it out, that what married couples should be doing. Understand what she needs when she said she wants some extra allowance?. is she paying for her own car and her own expenses is still quite high?.