How much to big are your pin wheels? your solid and your pinwheel blocks must be the same size or your corners won't match. If you trim too much off you will lose the points on your pin wheel. Does the 5 inch block include the 1/4 seam? are your seams the right size? Before trimming I'd check seam size and all my cutting measurments. Could you have cut your pinwheel pieces too large? I would check everything before trimming. Once you trim it off you cann't put it back. Good Luck , let us see your finished project.