If your machine sews at an even tension when you are straight stitching then your tension is fine. Are the feed dogs up or down. Personally I keep my feed dogs up it gives me better control. Feed dogs down you can slide your quilt sandwich with more ease. Don't give up! Do you have someone who does FMQ that can show you their technique? Good Luck, keep at it, someday you will be so greatful that you did!