Your experience is the standard experience, because the simple fact of the matter is (despite the legend and popularity of the pump) that simple pumping will never permanently increase the girth of your dick. A simple understanding of the anatomy of the penis will make this clear.
Anatomy of the Penis
The shape and size of the penis is determined by the 3 tunicae albuginea that run the length of the shaft beneath the skin. The tunicae are made of the same material that surround your eyeball and your testicles. This is very tough material and is very resilient to stretching. If you put enough tension on the tunicae, however - by stretching, bending, etc. - you can cause them to grow.
Why Pumping Doesn't Provide Permanent Gains
In using a pump, guys try to put vacuum pressure on the skin and the tunicae from the outside. Unfortunately, once the penis (including the tunicae) reach its natural erect size, any increase in pressure in the pump causes fluid to build up between the skin of the penis and the tunicae below the skin, so there is insufficient pressure put on the tunicae to cause them to grow. If you could actually put the vacuum pressure on the tunicae themselves, pumping would work amazingly well. The trouble is that there is space between the skin and tunicae, and that simply fills up with fluid.
This is the same principal why pumping will not increase the size of your testicles. Sure, your scrotum will get bigger, but the pump is not putting any tension on the tunicae of the testicles, so they stay the same size and the area betweeen the testicles and the scrotum simply fills up with fluid.
Just remember, every time you get fluid build up, it's actually called edema. It's what happens when you've damaged the body. You get it when you break or sprain a joint, you get hit too hard, or you pump too much. Fluid build up is a sign that you have done something wrong to your body.
Urologists routinely recommend pumps for guys with ED to get their dicks to their fully erect state. Every one of them that I've ever heard or talked to warns that going beyond the fully erect state can damage the penis and cause ED, so beware. Using a pump can have a negative effect on erectile quality. Have you ever seen a picture of a pumped dick that looked erect? No, they always look blubbery and semi-erect.
Guys who pump will definitely notice an increase in size, but it's not a permanent increase. It's just fluid build up. In order to maintain this increase in size, you have to keep pumping. If you are willing to do this sort of "maintenance" then, by all means, go for it. Just be honest with yourself about what it is you are doing.
Jelqing and Bending Provide Permanent Gains
Jelqing, on the other hand, actually forces blood into the tunicae and puts pressure on the tunicae from the inside. This method does actually work to increase the size of the tunicae, and thus the penis.
Bends also put tension on the tunicae and cause microtears, so they also can increase the size of the penis.
Bathmate Stretch
One exercise DLD does with the pump is the
Bathmate stretch. This can work to increase size, because it's pulling the entire penis, along with the tunicae inside, away from the body and thereby putting tension on the tunicae and on the ligament. Because the ligament sometimes retracts after being stretched, though, using the
Bathmate stretch can sometimes result in turtling. Nevertheless, some guys claim to have acheived permanent gains using this technique.
Choose Exercises That Hit The Tunicae
Whatever technique you experiment with, first learn the anatomy of the penis and ask yourself how is this exercise hitting the tunicae? You'll make must faster permanent gains if you do exercises that actually target the tunicae. If you simply like the look of a big fat dick and don't care if it is that size permanently, then go ahead and use the pump, just be forewarned that there is evidence that it causes ED.