Is it possible for the pocket to be made too small?

It would be really unusual for the pocket to be too small to accommodate your implant.  Even if it was tight to begin with, it should have loosened up.  Are your implants above or below the chest muscle?  That might have a bearing here.  It sounds more like you have a capsular contracture.

I suppose it is possible, but if the implant was placed easily then the pocket was likely not too small. On the other hand, you may be experiencing a capsular contracture causing the pocket to become tighter.

While it might be possible that the breast pocket was made too small, or the implant chosen was too large, however the cause of roundness and tightness is most likely capsular contracture.

Yes, I think it is possible for breast implant pocket to be made "too small" but I think it would be very difficult for a plastic surgeon (second opinion) to determine whether the breast implant "pocket was made too small"  as opposed to a patient developing excessively tight capsule (encapsulation)  around the breast implant.  Best to follow up with your own plastic surgeon or seek additional opinions with well experienced board-certified plastic surgeons. Best wishes.