Help! - bottle feeding

Omg I'm so overwhelmed and stressed. Baby boy just turned 3 months yesterday and I've been trying to get him use to taking a bottle and formula but he won't. I need to get him ready before I go back to work. He only finished one 4oz bottle last night but otherwise has been refusing bottles and not even breastfeeding properly from me either. I'm using dr brown wide neck with size 2 nipples and mixing 2 oz Enfamil neuro pro with 4 oz breastmilk. I can tell my supply is dipping from how much I'm pumping out and don't have a massive freezer stash. I'm so stressed out. Help! Help! Help!