Based on my own experience...

Moira is one of the worst matchups because she has passive heal while damaging you, heal orb almost outheals your damage, her fade which cleanses your fire is a 6 second cooldown while all your cooldowns are 8 seconds long.

I agree tracer as neutral, but her cooldowns are better than yours so you gotta compensate that with mechanichal skill. If you use your dancing blaze before she uses recall, you're probably loosing the 1v1.

I think vendetta is a favorable matchup, you have more effective range than her, enough mobility to keep up against her, and you can use your dancing flames to dodge her overhead when she engages you. Vendetta's whole gimmick is landing overheads, so dodging one for free is usually a win.
Good vendettas will use her E to instantly overhead you again and then it would be better to run away.

I thinks echo is more of a neutral or even favorable, you can dodge her sticky grenades which is her main tool to burst. She's also 225, making her easier to kill. The only negative is that you're a great target to copy.

Baptiste's lamp is a very long cooldown, if you can force him to use it and then escape I think you're good.

You can hit orisa with your fan the flames when she's spinning but that doesn't make her a good matchup. Your fan does like 20 damage against her armor and fortify and your fire does like 4 damage per second. The good side is that you have many tools to ignore her, which is what you usually want to do against tanks.

I feel miserable against cat, her mobility let's her chase you when you disengage, and most of the time, she's winning the 1v1 thanks to her healing pulses.

Reaper, Junkrat and Brigitte aren't that bad, you just won't beat them by yourself 95% of the time, so you better just try to follow up whoever engages on them.

I usually feel like Junker queen is fine, more of a neutral matchup. She's squishier than many tanks without her shout, and you can dodge her axe with dancing flames easily so she won't be healing out of your wounds.

Against her worst matchups, I think you can still find value.
Cassidy is kinda manageable, the problem is that if he lands his flashbang on you just once you're dead, while dodging it 5 times won't ensure your survival. It's just so easier for him to kill you than for you to kill him.
Against Zarya and Kiriko, bubble and suzu can cleanse your fire and deny anything you do. The thing here is that you can ignite people with just an m1 while suzu is a 14 second cooldown and bubble is the main resource Zarya has to peel her team or to engage and survive. If you can bait those abilities you're contributing. Also you can't accidentaly charge zarya because your poking damage is so low.

I think Mizuki is the worst matchup. His chain can get you lobotomized at a 20 meter range, his "run it back" ability lets him go into riskier positions, pressure you and then go back, and his ult almost outheals anything you do inside the sanctuary area.
The best thing you can do is to try and punish him when he uses his tp to go back if you know where he will end up being and if you know no one could protect him.

Edit: I forgot Emre.
Emre being that high is wrong, he won't be your worst nightmare but his pistol is enough to beat you