How to sew good fitting clothes WITHOUT a pattern?

The trick to it would be multiple measurements and multiple fittings. Sewing is like putting a puzzle together sometimes you just have to keep trying. If your garments are fitting better without a pattern then just be creative and continue to make outfits from scratch. You seem to have a very creative/artistic eye, good luck with your sewing. Growing up my mom made all our clothes and I can't tell you how many times my mom measured the pattern piece against my body to check for sizing.