Bottles a day

My daughter is 15 1/2 months old and drinks whole milk out of her sippy cup she has about 3-4 bottles a day and constantly has milk in her sippy cup when we’re out and about and for bed time and nap time

Her dr recently told us to only do morning and night time and the rest water ..

how could I make this transition easier for her?? She’s like addicted to her milk and it makes going out and car rides sooo much easier

Any tips will help TIA