Car seat/stroller

Hello, my son is 7 months old. We weighs about 20/21 pounds. I have the maxi Cosi zelia 5 in 1 stroller and car seat. I feel that my son is not comfortable in the car seat anymore. The width is a little narrow and I feel that it’s too uncomfortable. He’s turning one in May and I don’t wanna waste any money buying an “ infant “ car seat”.

Any recommendations?? I’m a new mom and don’t know any products.