Regardless of adds and stuff, your main issue was not being comfortable with the Vexie fight here, causing you to have downtime over 20% of the fight. You quite literally didnt use a GCD on the boss for 20% of the fight, that's a disaster for parsing.
You want to kill bikes but jumping into them is not your job. Healers and offtank are the best bike senders and it's not close.
Stay on the boss, the boss should move towards the bikes. If you're unsure how to move - stand on the main tank. He's the one to move the boss, you will never be awkward in trying to catch up to the boss while running through the bosses oil puddles if you just stay on the main tank and move with him.
Your Opener is completely unpracticed and unresearched. You're kinda just pressing buttons and you barely even charge as part of your opener. That is really really bad. One opener you spend time clicking RB into bladestorming without enrage (you NEED to be enraged in your opener ASAP, that shit is mandatory) and the other opener you spend 8 seconds doing inbetween stuff before going into bladestorm + roar.
Here's what you should do:
Combat start (let someone else pull) > Recklessness > Charge > Avatar(+potion+trinket) > Charge arrives at boss > Rampage > Thunderous Roar > Bladestorm > Raging Blow until enrage runs out (to stack Brutal Finish and Slaughtering Strikes) > Rampage
I heavily recommend you practice this opener on dummies. To get put into combat on dummies, you can taun the dummy. it's important that you get put into combat before clicking Recklessness because you'd otherwise lose rage meaning you cannot rampage after charge.
Since downtime is a GIGANTIC problem for you, you should watch videos of critcake or other warrior POVs in my opinion. Watch how they move with the bosses. You were afk not hitting sprocketmonger 1/3 of the fight for example. This is your biggest painpoint to work on.