From the start, I haven't pruned my peach tree like I should have. It's about 4yrs old now and overgrown. Is it too late to take control?
It isn't too late. Since you won't be able to keep any first year branches, you will not be able to get much fruit next year. Following that, with regular pruning, you should start to see good crop production.
Prolific--fruit set on in clusters like grapes. Largest ripe ones almost 3" tall. Orchard is in Klickitat County, WA. Sorry. No photos taken.
Without photos, this will be very difficult. In this case, I would suggest taking samples or photos to your local extension service. They may be able to help:
Here is a collection of articles on peaches that you may find useful: