Do you use the harmonics of notated pitches rather than stopping the string when it's convenient?
I remember when I had first begun playing, and my teacher was of the opinion that those harmonics, such as the first G above open, were convenient stepping-stones as well as markers for position. I agree, but never took the time to play otherwise.
Now I'm working on Dvorak "Romantic Pieces" (Ludwin), entirely in thumb positions, and I'm reteaching myself how to play in this position without using harmonics.