First, this outlet is in what was once a balcony. The drywall was placed over stucco so there's about a 1/2 - 3/4 inch of stucco followed by a gap (1/2inch ish) followed by 1/2 drywall. The original outlet was an outdoor outlet in the stucco so with the extra inches the junction box barely reaches the outside drywall.
The hole was cut bigger than it needed to be and then the faceplate was used to keep it flush then it was given a coat of silicone around the face plate (probably so it couldn't pull out. (All this was done before my bf bought the place and no one noticed it before or just ignored it)
I plan on plugging a PC into the outlet (only outlet available) and really don't like the fact that i can literally pull it out the wall. (But at an angle because the armored cable going into the box is just slightly too short to make it without pulling hard) How on earth do I fix this (preferably without having to completely rewire as it's out of budget)
There is a stud nearby, so my idea was open the drywall a bit more attach current box to stud as forward as it can comfortably go then add an extension to be flush with the drywall and then fix the giant hole i just made.
Unless there are other ideas that require less mess, or ones that are better up to code. (I have other ideas but I'm 100% certain they wouldn't pass code)
Edit to add : there is only a 5 x7 inch hole in the stucco partially (read: mostly covering the front) covering the stud. I unfortunately do not have the means or expertise holding a saw to cut through * (I have a hammer and hand chisel though) it so although i can make the drywall hole bigger i (at the moment) gotta work with the stucco hole. I have moved the outlet over a bit and managed to get a bracket to hold the outlet forward. So it stops falling back looking into getting replacment "old work" side supports and may (most likely) add some wood behind the drywall to add even more support) at the moment,
Second edit update: finished. Screwed the box to the stud and then used a metal extension to make it flush with the drywall. Have to say I think I did a pretty good job. Outlet is solid now. Still need to cover new drywall seams but very proud of myself first time I've ever cut into and replaced drywall or even fixed an outlet so it didn't wobble or pull-out.
Wanted to say thanks to all the answers (all very good answers) and hopefully this helps others who may have a similar problem. I know feel confident enough to do some other things around the house ive wanted to do now. So again big thank you to all the wonderful answers. Oh and I used the lipstick trick to find where I should cut the new hole for the outlet, worked well enough cut a little to high on one part but still worked out, it's a nifty little trick.