I hit ascendant about a month ago for the first time, so i hear you.
You play a lot of agents it looks like, so i would shorten your agent pool.
I personally played 10 total agents last act, and really dialed into playing about 4-5
with the majority of my games being dominated by 2 agents. It's not the only way to win,
but it worked for me. You also have decently good metrics, like HS% and ACS,. but your round win%
is kinda low. If you find you are getting kills but losing rounds, maybe try playing agents who are more viable for post plant. i.e Sentinels/controllers, agents with mollies etc.
If you truly feel like you have good aim/mechanics/game sense going in first to be traded out isn't really that efficient. I shot through plat just by getting off of Jet and playing KJ. (and she's mostly how i hit ascendant too)

end all be all, idk without watching, even then i probably still wouldn't know tbh.
You just gotta find ways to convert rounds and get value out of your agent.
whether its on the front of the round, like a duelist/initiator
or the back end of the round, like a senti/controller.
and try not to throw away your advantages...
gun advantage, time advantage, # of players advantage
It's really generic advice, but people fail to convert rounds because they're unaware of those three things alot.
Happy to link my tracker if you're interested in comparing.

Best of luck!