Hi, I'm new to quilting and made a "practice" one which will now be my dog's new bed quilt hahaha (I goofed up a lot on it but learned a lot too) Anyway, when I went to sew the batting and backing to the top, I can feel some of the seams where I sewed the top blocks together. I can feel them when I touch the back of the quilt. How do you keep from getting those seams? I tried ironing the seams flat but they don't stay down. Thanks