I find I NEED a gun of each type as well, but there are a LOT more types than just electro, pump, and pistol.
Electro poppet, electro spool, these overlap with the categories of electro uncapped semi and electro capped.
Mechanicals including mech stacked blowback, mech in-line blowback, mech autococking which overlaps with mech closed bolt, mech blowforward (currently missing this one, it pains me), mech fullauto (got two of these
), mech old school heavy metal (see avatar), and a few others.
Pumps include (and there's a lot of overlap on this one), pump stock class pistol, stock class long gun (don't quite have one of these yet), pump open, pump modified stock, pump sheridan based, pump nelson based, pump knightmare based, pump sterling based (missing this one), pump brass, pump aluminum, pump plastic, and of course wood.
There's the aesthetic categories of Sport (aka "speedball" but I find that to be a rather silly name since the guns don't care what field they are on), Military, Military-Tactical (or mil-tac, signifies a bunch of rails on a military styled gun), Sport-Tactical (bunch of rails on a "speedball" gun), Mil-Sim, and Sport-Sim (like mil-sim, but nothing military about it, mag fed "speedball" gun). Still working on filling out these categories.
Now I've been known to go through 6 or 7 guns in a day, changing up styles to match the players on the field, the field we're playing (often going the opposite of expectations, just for fun, my T9's first elimination was on the airball field), and of course how much paint I have left.
You probably have too many when you end up buying a gun you just can not use on the field. I have two of those, a pair of .80 cal Stingrays. Or you buy a gun and manage to forget about it until you stumble upon it while cleaning out a closet (guilty again, twice).