Hey electricians. Me and my partner recently had some funky electrical stuff happen in our apartment due to our bathroom and 2 bedrooms all being on the same 15 amp circuit when we plugged in our portable AC unit.

After plugging in our portable AC into that same circuit(we know now we shouldnt have done this) we started noticing weird things with our electronics. We've done this for 3 years and never had an issue.

Anyway, we reached out to the leasing office and asked them to send out an electrician and they did and they tested everything and everything seemed fine except we really shouldnt be running this AC on the same circuit as 3 rooms. 

However, being on the 3rd floor of an apartment with no central air, it gets HOT, 100+ degrees in our bedrooms. 

The electrician told us to get a 50ft 12 gauge extension cord and run it from our 20 amp circuit for our washer, and just unplug one when the other is in use. 

So that's what we did, we just got it all roped around the apartment, got the AC blowing cold air and that's great...but then I start reading other reddit posts strictly advising to NOT do what we are doing. 

We move out in 2 months to a place with central air. 

Is this going to be safe? Our apartment is just unlivable otherwise. Its at least gotta be safer then having it plugged into the same circuit as 2 pcs, 2 ceiling fans, several lights, chargers, consoles etc etc right?? Please advise someone who knows nothing about anything, thanks :) also here's a picture of the specs on our portable AC

Portable AC with 50ft 12 gauge extension cord.