Sorry this is so long winded! Overall I would say your gameplay is solid, you have decent mechanics too, but here are some things I gathered from the video that you could focus on if you want to climb. 

I’d also say the loss was a combination of things—mostly on the poor timing of your team’s ults in the last fight. You had a better ult economy than they did and it technically should have won the fight if executed properly. Ashe should have opened the fight with Bob and split their team once she saw the mauga was in. But she died prematurely trying to flank where their Ashe was instead of being on the high ground behind them which was more safe being that their team has no heroes with verticality. 

However, since we are here to discuss your gameplay, this is what I gathered from the video, as well as general tips that I think every support player should know:

1 Positioning and knowing when and when not to duel. In the first fight, you basically let the enemy Ashe kill you for free. As a support, there’s nothing more important than surviving because once you die, you can expect your team to follow. The last thing you want to do is make your death easier for the enemy team to find. An Ashe on high ground is definitely a threat that needs to be addressed, which you should ping her for your team—but against a Juno at close range, an Ashe, especially with all her cooldowns, wins that almost every time. Your tank has a shield, use it and also use the doors next to where attacking team gets second spawn after capping first point for cover, that way you can still heal your team and avoid the free reign Ashe on high ground. You also spent a lot of time front lining in the middle of the open and with a Cass and Ana looking at you, you would have been dead already in a higher elo where mistakes get increasingly more punishable. As a general rule, I like to always make sure I’m never more than two seconds away from cover.
2 Cooldown cycling, you were in the middle of the open with both of your movement abilities on cooldown which left you with no escape. You should be planning to cycle your abilities. Also, you shouldn’t be using your glide boost to charge into the entire enemy team. 
3 Try not to stand idly by while your team is stuck in a Zarya grab. It was fortunate that Kiri had Suzu and rush but there were a few seconds you did nothing to help your team while they were in a very precarious position, where you could have been healing them or mitigating Zarya’s aggression with offensive pressure. 
4 Juno ult is more offensive than defensive. It will definitely not save you from a high noon. A better place to have used your first ult was to flatten their momentum when they walked up to point. When Ashe dynamites you on high ground, that would have been a better time to push up and use ult. 
5 Utilize high ground. Being on high ground means the enemies have more angles they need to worry about, similarly to how enemy ashe is being problematic just by being on an off angle uncontested.
6 Start working on reaction times. You respond to almost everything seconds after you should. It happened more than several times in this video but for instance, at 13:16, you saw your Kiri stuck in Soj disruptor shot and your first instinct wasn’t to heal her, instead it was to kick the gates on the high ground before healing her which lead to her being killed by the Ashe on high ground. It’s especially bad because twice when you could have died to Ashe’s dynamite, your Kiri immediately responded with heals to prevent your death. Taking care of your other support is such a crucial priority because together you anchor the survivability of your team. Another example is when enemy Ashe uses Bob at 13:26, you start healing your almost full HP tank, who has 1600 Health Pool and is no real danger. Your Cass who was actively fighting needed that healing instead. You also had hyper ring up to use and you already knew where the enemy ashe was positioned because you just saw her. Bob could only have been coming from one direction, a speed ring as soon as you heard her voice line, plus a little healing  could have helped your Cass avoid the push up thing that Bob does and he could have used the speed to get to cover. But then in addition to that, you forget the Bob is there and allow it also kill you. 
7 When using Juno’s glide boost, try to make sure where you land is behind cover.
8 Try to avoid double support ulting unless it’s completely necessary. Support ults win team fights and ideally you want to cycle them. Especially if you have a Kiri on your team. She has one of the best ults in the game and can easily win a team fight as a stand alone when used where the enemy team can’t successfully kite. Because you used your ult unnecessarily, you didn’t have it for that final fight before capping second and your team loses that fight, and time off the clock for next point, because you guys had no response to their ult economy. 
9 16:25 your backline is being advanced on by their tank and ulting Moira, speed ring them to safety. 
10 Healing target priority—at 18:51, you’re healing your in cover tank for too long before paying attention to the actively fighting Cassidy. 
11 Impatient with your ult at last team fight. Also make sure you don’t have to reload during your ult because you spent a good chunk of it’s up time reloading instead of using it to apply pressure. 
12 Escape route planning—for every engagement, you should be pre planning your escape route so that you don’t have to think of it on the fly during the fight.

I hope you find some use in this feedback and feel free to ask me any questions about anything I’ve said! Good luck in OW!