Added girth gains should make your penis actually look smaller. Just like added length gains should make it look thinner. You're really use to seeing your dick one way, once gains become noticeable your brain will think, why is my dong looking shorter? Bad day I guess... When in fact it's due to an increase in the circumference.
I was looking at mine a few nights ago before I fell asleep. Had a 10/10 EQ erection, but it looked small. Stuck that fucker straight up in the air, still looked smaller than normal. Wrapped my hand around it, noticed my fingers don't overlap nearly as much, and realized I may be getting some more girth.
It's even stranger when you make a 'jump' gain. As in, a large change in a shorter period of time (especially if it's only one, not both). When I jumped from about 7.5-7.75 in about a month, it looked like I had a pencil dick. I gained almost no girth in that time (1/8-1/16" total I believe... mostly base girth). It still looked as if my dick got skinnier, rather than longer. Your eyes will play some tricks on your during the coarse of your PE adventures.