Sippy Cup for breastmilk

My baby is 9 ½ months old. I’ve been working from home and just breastfeeding but will have to go back in the office soon. Our pediatrician said to not re-introduce the bottle but rather to give milk in a Sippy cup. Any recommendations? Looking to find one that won’t cause my baby to waste a lot of milk. He has the Munchkin Miracle 360 that he drinks water out of but so much water ends up on his shirt so I’d hate that to happen to my Breastmilk. Thank you!