I'm having trouble distinguishing these sounds from 'j', 'q', 'x'.

My teacher says my 'zh', 'ch', 'sh' sound too much like 'j', 'q', 'x'. I understand that the first group should be "retroflex" (tongue curled back), but I can't seem to get it right.

Any tips or resources that helped you master this distinction? I've been practicing for weeks but still can't hear the difference clearly.