Watch out dude! What you're doing will make you HUGE!!!!! Haha, no, I'm kidding. Don't worry, you really can't build any substantial size with only pushups and stuff. I mean, you can get some size, but it's really only noticible if you're naturally skinny. Don't expect to look like Arnold, though.
I'm not saying you want to look like a bodybuilder, but why are you so opposed to size? When most people get a little size and definition they start thinking "hey, I look pretty cool." Hehe. Who would you like to look like? Bruce Lee?
Anyway, if you want to get strong without gaining size, then low reps and high weights are the way to go. Low numbers of sets, too, like two sets per exercise. But only do core exercises, such as bench press, squat, deadlift, pullups. That kind of stuff. If you keep the low reps high weights thing but you do bench, then dumbell flies, then triceps presses, the triceps pulldows, then shoulder presses, you will lose it's strength building with no size effects.
If you are really interested in this (getting strong without getting big), get a book called "Power to the People" by Pavel Tsatsouline. Using his methods I have set multiple new personal records in bench and deadlift and weighted pullups without putting on any weight at all.
IronFist
"If you like metal you're my friend" -- Manowar
"I am the cosmic storms, I am the tiny worms" -- Dimmu Borgir
<BombScare> i beat the internet
<BombScare> the end guy is hard.