My landlord is not fixing anything around my one bedroom converted garage!!!!?

I feel that he is taking advantage because we are young. We are always on time with the rent, we have talk to him about the fixes that needs to get done inside but he doesn't fix them. I don't know what else to do??? Or if I should take legal actions because I have three littles ones living with me. I don't think it's safe or sanitary for them. Example, the bathroom mirror is rusty and moldy...