I have finished knitting a sweater. The sweater was knit all in one piece. I have sewn the side using the mattress stitch, but I'm not sure if I should also use that for the sleeves. When I was knitting the sweater, all the increases I made for the sleeves have created what look like steps on the edges. When I try to sew with the mattress stitch it does look right. I'm not sure if I should use that or another stitch.