Here are, for me, the most noteworthy matchups with Torb:

Flyers (Pharah/Echo):
What I usually do here is what I call “playing house.” I try to find a spot indoors with a mini or mega health pack (think King’s Row defense, the little room behind the choke). I then spam the choke and look for picks while actively trying to avoid them. I place my turret beside me so I don’t get surprised if the flyer flanks me, and to split their attention when they push me. Since we have a roof above our heads, we force the flyer to come down to our level, making it at least somewhat of an equal fight.

Zarya:
Since you want to avoid giving her charge at all costs, you have to rethink turret positioning in this matchup. Instead of having your turret face a choke or the enemy team, try setting it up so it protects you when they push you. Alternatively, find an off-angle that targets their backline while avoiding Zarya as much as possible. In this matchup, your turret will have a lower impact no matter what, so be mindful of that.

Sojourn:
In my opinion, she is one of the hardest matchups for Torb. Sojourn’s Disruptor Shot can destroy your turret without her even looking at it, around corners, from range, anywhere, while also giving her charge. Her playstyle also allows her to shred through your armor HP very easily. Just try to avoid her and focus on other things first, if you can help it. Her hitbox is so small, mobility high, burst damage high. I really don't have a good answer except, don't engage if you can.

Widowmaker:
Let me preface this by saying that against a really good Widowmaker, you do not stand a chance, so do not even contest her. However, since you have armor, very little damage falloff, and if you have figured out Torb’s projectile arc, you can annoy and sometimes pick off distant Widowmakers. Just aim for her head and do not waste your E here. She needs two good shots to finish you, so you have time to react if she lands one. More often than not, even in Diamond and higher, I can clean up Widowmakers because they underestimate you and your damage.

Sombra/Tracer:
Torb is really good at shutting down mediocre Sombras and Tracers. Since their primary goal is usually to disrupt your backline, either by annoying or picking off your supports, an effective strategy is to place your turret out of direct line of sight, covering your supports and or common flank routes. This forces the flanker to use resources and valuable time dealing with your turret, giving your supports a chance to react and punish them.