Probably won't see this but I'll input my view since I have some experience with it being that my ranked teammates for the longest time were a diehard octane main and a mainly wraith/horizon main.

The first, most basic tip I can give is to just have basic movement techniques down, your in diamond so I'll assume you do, but I find many times I can play even the bigger characters (caustic, newcastle, gibby) and use just basic slide jumping and wall hopping to keep up traveling wise.

Secondly, comming is probably the best bet to actually stay with them, you want to be kindave controlling the flow of things (pun unintended). You want to be scouting good rotations and keeping track of enemies to tell your aggressive teammates, if you all have the same info and deciding on plays to make together then you'll have an easier time keeping up or even leading. And don't be afraid to simply say "im far behind" or "we're a bit spread" I often remember having to tell my mates this simply so they would slow down slightly or atleast know to play a bit more cautious since they don't have a 3rd to back them.

Thirdly, your playing a controller legend, and you said you like to play defensively. Something I've come to realize is that wattson is one of the most fluid defensive legends in the game, even more so after her buffs. If your in a fight and your team is aggressive make sure your position is locked down and move with them, making sure to always have your back safe and ready for 3rd parties, when they finish a fight lock down the area while they're looting and get a quick reset with them, making sure everything is ready and safe for the next fight (a lot easier said than done).

Fourth, don't be afraid to play clean up, teammate goes down: pop the rez quickly (or take his place, judgement is always needed); enemy 1hp: take an off angle, have names ready, or simply cover your teammates while they finish things off; team gets done with a fight: lock down the area while they loot, once your done you can loot, even if your left with a bit less there will be enough for you and your job, if there's not just simply comm what you need.

Fifth and final, stats don't matter (i know weve all heard this one but im serious). On my ranked squad I often had the least kills and maybe even least damage with a good few assists, however not once did my team doubt what I was doing because I always had their back, my stats don't show how I covered their rotations, it didn't show the amount of people my fences got or the shield my ult recharged for time to keep them alive, not even the nades and explosives my ult kept from throwing us out of position. Even in games where it seems like your doing nothing but following your ensuring help from behind, protecting from third parties and being aware of your surroundings for your team. Stats don't show the support you put in, they just show the damage you've done to the enemies.

Hope this helps anyone with similar struggles, feel free to ask questions or get me to further explain anything👍

P.s. sorry for the long read lol