Weaning

So I'm having a really hard time weaning my 5 month old during the day I'd like to keep nursing at night but I'm getting ready to go back to work and school I've tried different types of bottles and having my dh and a few close family members who would be baby sitting give him the bottle he just won't take it and we've tried everything I can think of and now I'm looking for suggestions on what I can do I need to go back to work but I don't want to just wing leaving him with my sister and hope he takes the bottle I want him to be comfortable with it please help