hey man, i don't think that's underperforming at all. you've managed to up the weights a bit from your previous workout - thats great in itself. i think darklight has said that HVT is instinctive, going with the feel.

sometimes i too feel somewhat weak, tired etc on a particular day - no sweat, all of us have that one day off. just come back the following hitting hard and strong. also feel free to keep increasing the weights you do, even though if it means cutting down a two or three reps. you'll be able to build upon that the next time you do a chest workout.

what i normally do is alternate machine chest press with incline dumbell bench presses every other week as it helps to build the upper part of your chest as well as balance.

pushups are fine, in fact at the end of each chest workout i usually do one or two sets until failure to really exhaust the muscle. anyhow, keep us updated.