That sounds incredibly painful! I'm sorry that happened. Pressure washers are no joke.
I wouldn't apply petroleum jelly. If, for some reason, undesirable bacteria were to enter your wound, the jelly would simply trap it in the wound. If you're having issues with the bandage sticking to the wound, a small amount of jelly won't hurt, but don't slather it on.
Most sources state the consultation with a medical professional is needed, but I understand why you'd forego that if you're healing and not seeing any sign of infection:
This one states that you shouldn't bandage the wound after a few days, but continue to use antibiotic ointment: https://www.mountnittany.org/articles/healthsheets/36606
I did find a source that states you could be looking at 12 weeks for the skin/scar tissue to complete re-cover the wound, but hopefully it will at least be "sealed up" before then so it's not so raw.