(1) "I don't lift as much anymore but I'm bigger now" perhaps, but you are still strong as a MFer and one of the strongest in your city, or you aren't actually big but merely "bigger than before"
(2) "it's about squeezing the muscle not lifting the weight" yes but unless you can squeeze the muscle with heavy ass weight you won't be truly big
(3) "you need to be strong in all rep ranges to be big not just 1-3 reps" yes but before you can do heavy ass weight for 12 reps you'll have to do heavy ass weight for 1-3 reps
For example, last chest day I did 435lbs on bench after hitting 405lbs once, but I failed halfway up. Today after hitting 405lbs once I went up to 500lbs (well 495lbs but it's five plates per side so I'm calling it 500 lol) and just lifted it off the rack, moved it forward above my chest, and held it in my hands for 25 seconds as my arms wobbled and shaked. Now my body is used to lifting 500lbs and I plan on hitting that as my new 1rm within a month or so.
OP- I'm curious to know more about your football career. Is this college, semi pro, NFL, flag, pick up league, 7v7, CFL, Arena?
Nah it's "semi pro" but all that is is a glorified adult tackle football league. We wear full gear, helmets, pads, and play in high school stadiums with referees. It's a real game, lots of ex college players out there, but no one is getting paid, and anyone who wants to play can join the team (although they won't get playing time if they aren't good enough).