Need advise on downsizing cylinder

Right now I have a LeLuv 2.125 inch wide flange cylinder. I have been using it a couple of weeks, but I think it might be too big. I would like to straighten-out the leftward curvature and also increase length more than girth.

Currently the length is around 6.5 and the girth is around 5.75 inch, but it is difficult to be exact.

When I use the cylinder it seems too push against a testicle or something at the beginning which is painful, so I increase the vacuum slowly. After a while that testicle pain goes away, and the base of the penis packs the cylinder about 2.5 inches up. Due to the curvature, the left side of the head rubs against one side as I increase the vacuum on and off. (I have been using an electric pump with a program that increases the vacuum over about 10 seconds and then immediately releases the vacuum, and then repeats. I thought this would help to stretch the penis without getting the fluid build-up. I typically increase the vacuum to around 35 kPa (10 in Hg) at most. This is painful if the vacuum is held for any time, but the program only holds it for a second and releases.

So there are two smaller cylinders. There is a 2.000 inch wide flange and a 1.900 inch thick wall. I am leaning towards the 1.900 inch, but I hate to buy the wrong size. Also the thick wall requires a hose adapter to work with my pump, and I get the impression that thick wall is not for novices like me.