It's a little hard to tell from the angle of the picture but that pinky looks ok.
By "different kind of pinky" should we assume that the store moved you from mouse pinky to rat pinky? (again, hard to tell but that would be bigger)
Rule of thumb is to feed a meal that is about the same size as the thickest part of your little guy.
A little smaller is what most ppl go for and a (very) little bit bigger is ok also. If he doesn't want to eat it because its too big, you will find it sitting there tomorrow! (a gift...for you!)
Just remember that when you feed the 'hefty' meals you might want a longer interval between meals.