My twins are getting so big toooo fast?

im 17 years old and i have 2 month old twin girls Madison and Mackenzie, their dad and i broke up two months before the girls were born, they were born by emergency c-section when the doctors couldn't find Madison's heartbeat. they were born 1 month early and were kept in the NICU for 3 days and were able to go home with me. now they are two months old and i am now starting to find that trying to take both girls anywhere is a huge hassle. i was told to but them into daycare and only take one but i don't want them to grow up thinking i like one over the other. since madison is smaller than her sister i usually take her and leave mackenzie with a baby sitter. i am bottle feeding Mackenzie and breastfeeding Madison trying to help her grow better. i want to know if i am doing the right thing by taking only one twin places and not the other.