Sleep sack question for 3 month old

My girl is almost three months old. She keeps getting out of her swaddle so we want to put her in a sleep sack. The ones I have are fleece and have long sleeve arms. My question Is what should she wear underneath. Bedroom is usually 68-70 during the night. She was usually in a fleece sleeper but now I’m wondering if the sleep sack itself is fleece..isn’t that too much fleece!? She generally runs cold that’s why we had her in fleece under the swaddle. What do you ladies think?