I would not change my needle, you may have to slow down though. The sheet for the backing is not really a great choice for her, but people choose it. The sheet, at least in my opinion, falls similar to a tight weaved batik fabric. So if you need to adjust, it would be along those lines. What thread you using? That may be the trickier part than anything because tight weaved fabric needs a good thread. If were me I would lean more towards a poly than a cotton thread.