Alright, few things to note looking at the match in question
[1] Garen is not a heavy autoattacker, so Fervor of Battle isn't really a useful mastery on him. You'd have probably been better off with Grasp of the Undying or Thunderlord's Decree (or arguably Stormraider's Surge).
[2] You were not ahead the whole game. Until ~29 minutes into the game, neither team was more than 2k gold ahead of one another (with the leading team going back and forth). While your team had more Dragons, the enemy team had more towers killed.
[3] Their jungle Tryndamere had ~100 CS above anyone on your team except Tristana. Considering their Lucian was also decently ahead and that most of your team didn't break 150 farm in a 35 minute game, your gold was no where near as high as it should have been.
[4] Your team had very little lockdown. All you had for CC was basically Maokai's QWE, Tristana's R and Bard's QR, so you didn't really have a way to lockdown or kite Tryndamere for a noticeable amount of time.
[5] Tryndamere had a massive gold-lead on everybody and no-one on your team was actually capable of dueling against him. He could easily just split-push you to dead while giving his team a numeric advantage else-where.