Early position usually refers to where you sit at the table, this hand, relative to the Big Blind. The stages of a tourney, early, middle, pre-bubble, post bubble and late are usually referred to as stages.
So it looks like you have a good handle on the early stage of tourney's. Good.
Early stage will last about 3 levels of blinds, with the first level being the most dangerous as the insaniacs are running amok.
Once the table calms, and you are still in the first few levels, you need to read the table dynamics, who is doing what when and to whom? Take notes on individual players.
Moving into the middle stage, you should be seeing reasonably sound poker, and you might want to consider doing the opposite of what you think the table is doing. If the table is still wild and crazy, be calm and tight. If the table is tight, be the slightly crazy one. In tourneys this is where you need to steal 2 or 3 times every 3 or 4 orbits (this will keep you ahead of the increasing blinds without tagging you as a LAGtard). Add these steals to your normal winning hands and it will keep you in the middle of the pack. Not a bad place to be thru the middle stage of a tourney. You don't shove without great reason.
Key to my thinking has always been if I can stay about average, I will end up heads up.
Understanding the table dynamics here is crucial. Everyone at the table (presumably) understands it is bubble time, and has very likely gone uber nit. Good time for steals, but don't overdo it. Even with monsters you might want to consider not shoving. Play for value if you can, and be patient. You mostly want real made hands to get seriously involved during this phase. You too want to make the bubble, and there are opportunities galore during the pre-bubble stage.
You can't imagine how much relief many people get from just making the bubble. Everyone loosens up and shorties are thrilled and patting themselves on the back for making the money, and are in immediate need of a double up, so they will be shoving. Good time to refill your drink if your stack is fine. Treat the early post bubble just like the first several orbits at the beginning of the tourney.
In fact, in fractal like form, you can deal with the post bubble play just like it was a whole tourney all unto itself, with an early, middle, and late stage. The final table bubble (signifying the larger money places) will be similar to the pre-bubble game in the larger tourney.
So, it sounds like you start well, but then forget what your goal is. Goal #1 should be to make the bubble (and thus the money), and goal #2 should be to make the final table (and thus the bigger money). IMHO, you should avoid that 'I'm in it to win it' mentality until you are halfway thru the final table. While I agree that I don't get into a tourney to just 'make the bubble', I understand that I must make the bubble in order to get further, and that uber agro attitude about winning it just gets most folks in trouble.