Certified GKH Gardening Expert
Peach trees need to be pruned and thinned well to produce fruit. If your tree is at least 3 years old and it carries the immature fruit throughout the season, that may be your problem. Here is more information: https://www.gardeningknowhow.com/edible/fruits/peach/peach-tree-thinning.htm
If it's dropping the small fruit too early, check for small scars on the fruit. You may have an insect infestation. Neem oil (sold as fruit tree spray) will help.