Mommas who have multiples

My LO is almost 4 months old and for the past two months she will only take 30 min naps. If I want or need her to nap longer I will hold her. I love holding her but I don’t wanna make this a habit. I exclusively pump so if baby and I are not on the same schedule it makes it impossible for me to leave the house. Will her naps get longer after the 4 month sleep regression? Should I stop holding her? She sleeps through the night. We’ve been having trouble putting her down at night. Will be asleep and wake up, will go in to comfort her, she’ll go back to sleep but wakes up. Usually takes us 30 min to an hour to get her to sleep. She hasn’t always done this... am I creating a Monster??? Ha ha