First thing first. The baby is you and your husband's child. Not your MOL nor anyone else's. They need to respect and accept that fact. I'm sure when your MOL was in that situation she laid her ground rules.
Also your baby is a preemie and at 7 wks old is still very suceptible to infections. I too had a preemie so I know. My baby was 10 wks early and I had to be very careful and firm with people. Yu are your baby's protectr as she cannot defend herself. A lot more people will be offended by the stances you will have to take throughout her lifetime. That comes with the title of Mother. Congratulations on the birth of your daughter. Blessings
Your MOL should be more understanding and considerate.
Just my two cents.