Technique is a big deal and while I also do not have large hands and I prefer not to alter my grip during a reload, I have to use alternate techniques for various pistols which includes rolling the weapon in the hand to hit the mag release, which is of course weapon dependent. Ideally I would opt to keep the same master grip when performing a reload as I use when actually shooting. For a Glock pistol the Gen3's are not my preference, however the Gen4 has been more flexible for myself when it comes to maintaining the same master grip. So if you want to stick with your Gen4 Glock you are already ahead of the game in that they are easily modified to suit your needs. You can opt for a finger groove and/or a backstrap grip reduction. Also a Vickers style, or re-contoured gen 4 magazine release will help for smaller sized hands. The Vickers mag release or my own alteration of the stock Gen4 release puts the magazine release in a much better position to activate for shorter finger reaches. On the downside as far as I know no one else is doing my modification of the stock mag release. Also I am not aware of anyone else doing my magwell modification either.
The lower Gen4 G17 is what a finger groove reduction will look like next to a stock Gen4 Glock without any backstraps. This particular pistol has only a slight backstrap reduction to fit my hand. However it can be reduced more than what is shown in this picture. This picture also shows the Vickers mag release, a rounded trigger guard, undercut trigger guard, radiused trigger guard, texture job, fixed "pig nose", extended slide stop and a flared magwell. Pistol also has trigger work that comes in at a crisp 4lbs.

Better pic of the magwell next to a stock pistol. Also this modification helps with sticky mags/ magwells for a clean drop free mag release.

A couple more views of what can be done to the grip / pistol


Here is a Gen4 G19 with a stock magazine release that has been re-contoured for a better reach and operation of the release. Pistol also has finger groves removed, texture, undercut trigger guard, rounded trigger guard, radiused trigger guard, malfunction cut for magazine stripping, sights, also a trigger set up for a crisp 4.5 lb trigger.


So you really can do a lot to custom fit your existing Glock to your hand if that is the route you wish to go. I personally hand fit all of my Glocks. That is one of the appeals to the Glock pistol.