Here’s a technique to get a head swell with out the use of an extender. You want to be a quarter to a half inch from the head to avoid the dorsal nerve. Get a semi erection, and attach a clamp. Don’t clamp all the way down completely just yet. With it partial clamped push blood into the head till it starts to enlarge, once desired plumpness. Tighten the clamp till the blood stays and it’s comfortable. I urge caution on pushing a lot of blood into the head but a reasonable amount I like to be a bit larger than erection size.
Normally this technique is used with an extender to keep blood in the glans and added expansion to prevent slippage on harder extender sessions also helps keep things comfortable.
With the focus on the head only you should see all areas expanded.