The going off food definitely sounds like teething or a bug. We've had a few weeks like this - it really stressed me out to begin with but actually although DD lost some weight, she piled it back on once she was feeling better. I tried not to worry and if she refused or ate little of her normal food, I'd make sure she had cheese, yoghurt, raisins etc (all things she loved) which would normally tempt her to eat a bit.
You're probably right that you will need to start thinking about cutting down her milk intake, as you want to be giving a maximum of a pint (20oz) from a year including milk on cereal, in sauces etc. More than that can cause nutritional problems e.g. Iron deficiency as LO fills up on milk and doesn't get enough nutrients from solids. I would probably drop the DF first. Since you're bottle feeding that should be relatively straight forward - usually just decrease by an oz every couple of days if you want to do it gradually.
I might wait until she's over the teething first, then next work on dropping one of your middle of the day bottles. Again it might be worth doing an oz less every couple of days on the mid morning bottle, and gradually bringing your mid afternoon bottle a little earlier so eventually you end up with bottles at WU, lunchtime ish and BT. How does that sound?