My DD is 15 months old and was exclusively FF too. We used the playtex drop ins.
Here's what we did: at 12 months she was on 4 bottles: first thing, 10 am, 2 or 3 pm and 7:30 right before bed. She drank water out of her sippy cup with meals. So, after her 12 month appt, we aimed to cut out one bottle of formula a week and replace it with a snack. First the 10 am one, which was easy as pie, so we did the midafternoon one two days later. Those snacks were replaced with yo-baby, or crackers with hummace on them, a cheese stick, something like that. So one week into it, we were ready on the weekend to do the first morning and night time one.
First we did the first morning, and we replaced it with a sippy of milk. This was also easy, because she was pretty hungry at this point and would take it however. At first, just 2 ounces or so (and we moved breakfast up) but after a few days, she really LOVED whole milk and would give 8 oz if we let her (we don't, see below). The evening bottle was hardest for me (as it was the last botle to go) but easy for her, she never looked back. She was fine right away.
Now, that being said, I did keep the bottles for 2-3 weeks to see if there would be any regression if she got sick or something like that. And we triggered with the amounts. I was giving her 8 oz in the morning, but then she wasn't hungry for her breakfast of solids. So now she gets a 4 oz sippy first thing in the morning, then breakfast an hour later, snack at 10 am, lunch at noon, 4-8 oz of millk around 1 pm just before nap, snack at 3ish, dinner at 5:30ish, and 8 oz of sippy milk at 7:30 before bed.
Now... right after we did this, she started waking up in the middle of the night too. Molar teething it was!! But she was hungry. We found that the exercise of me taking her downstairs, pouring 2-3 oz of milk in a sippy, walking with it and her back upstairs, back to her room, putting on the cd player again, taking her lovey and rocking her while she drank her milk pretty much allowed her to go back to sleep. Once my husband went and got the sippy and brought it to us but that made her madder than a hornet. She wanted to go get it herself. Molar teething was off and on for 2 months. She would sleep fine 3 days, be up for 4 days, fine for 4 days, up for 7, etc. Now all teeth are in, and she sleeps fine.
So, that's our long winded story. I have been told to try not to give milk in a bottle, as the children learn that is allowed and will prefer it. Still, not sure that I would follow a rigid rule like that. We used take n toss sippies and now they are so easy, I woudn't go back to the bottle if you can get to the otherside of this.