Put a switch on my electric water heater, now I only turn it before I'll need really hot water..

[Fumesucker]

10. You might want to check the temperature of the hot water from the closest faucet to your tank..

Something like a meat thermometer will do it.

Some tanks do build up sediment on the bottom, it's hard to image that you could have 30 gallons of sediment though but I suppose if the tank was really old..

Keep in mind your shower may flow more than mine too, mine isn't particularly high flow.

Oh, wait.. I just realized what your problem may be..

Some electric tanks have two heating elements, one low and one high, if the low one burns out you will only have a few gallons of hot water in the tank.

ETA: I meant to say one element physically down low in the tank and one up near the top, if only the top one is working the hot water stays at the top and only from the upper heating element up will get really hot.

Yours is probably a tallish and thinnish sort of tank, look for removable covers, there should be one for each element.