Just noticed you are being held up by this. Something I seem to mention several times a week on this forum is Lazy Nezumi Pro. Not only does it let you draw amazing smooth brush strokes with long long tapers at each end of the stroke, it fixes things like shoelace artifacts (those blobby bits on the end of a tapered line), it also has a number of very useful line constraints.
IMO no tablet user should be without it. I also think it has a better than average chance of fixing your problem. Give the trial version a go. I think you'll like it.
Lazy Nezumi Pro - Mouse and Pen Smoothing for PhotoShop and other Apps