I'm so glad you decided to post your photographs and show us what you've achieved with your growth in 3 1/2 years. You certainly were determined to see your natural growth pattern. I'd love to do that myself but I know I've been grabbing the scissors when it's just too natural for me. If it were me, I would first decide what's most important and keep the length if I decided that was the most important. It sounds like length has been most important for you up to this point and that now you're reconsidering your priorities.
I would trim it by about an inch or two and then decide about trimming another 3 inches. So I'd do it in 2 trims.
Good luck whatever you decide and PLEASE post your new pics afterwards.
Martine
Length: 23?/33/36+
Hair Texture: wavy & fine to medium (Type 2a)
Color: dark blonde with light blonde highlights