very good sign!
got it, it may be best to place the rope near the hinges to account for the weight placed on them. however, if the door is fully closed and locked, then anywhere else should still hold due to the doorframe.
as for the doorknob, it would probably be more reliable to find any sturdy object that is cylindrical (rolled up clothes/towels, bottles, the handle of a dumbbell, etc.) or similar and tie your rope to that with a secure knot, then use that as your anchor point by placing it behind the side of the door that you are going to hang from, then slipping the rope back over. by "back over," i mean similar to your doorknob setup where the noose is on the other side from where the doorknob is, except the doorknob is replaced by the cylindrical object in this case. in both cases, the anchor is not going to counter your weight but to prevent the rope from possibly slipping through and letting you fall (like the anchor of a ship to prevent it from moving in water). the doorframe should account for said weight as i mentioned earlier.
door knobs in hangings tend to break and snap off easily so they aren't too reliable as an anchor.
if perhaps you know this already and i'm beating a dead horse, i apologize!
everything i said here was pretty much a summary of this much bigger
thread that you can look at to confirm for yourself.
additionally, here are the pictures i used as reference (from the same thread):
pic. 1,
pic. 2,
pic. 3
i hope this helps and wish the you the best. if anything i said was confusing, let me know