The ball point needles are usually used for T-shhirt quilts and knit fabrics. I have used them for that purpose and it works really well. The ball point needle is designed to separate fibers without cutting them. I use size 16 or 18 sharp needles to quilt on cotton. Your stitches are fine. If you wait for a while and let the fabric relax, the holes start to close up. If it bothers you, switch to a smaller needle.