You have good reason to be worried on a couple of counts. The first is you never mix transmission fluids or change types. If the owner’s manual calls for Dexron then that is the type you have to use. It’s easy to make this mistake, if you don’t change transmission often, however it is a mistake that can cause problems as the specifications of the different fluids may not track the same. One could have more detergent and less lubricant while a second could be the reverse. Also, each transmission is engineered to work with a specific type of transmission fluid so if the type you have introduced to the transmission isn’t correct you are potentially facing problems. The second count is that you apparently didn’t refill the transmission properly — you said you “inserted a bit to manage the oil level … ” which seems to say that you didn’t properly check the level of the transmission fluid so you may have overfilled the tranny which brings with it other issues, many of which you describe.
Frankly, it seems much more apparent that, along with the issues that were just described, your transmission is just suffering from age and use. While Suzukis are excellent vehicles, they have one thing in common, their engines tend to rev like crazy and this can strain all parts of the driveline, including the automatic transmission. Granted, when an engine revs it is more efficient, believe it or not, than one that just lumps along as the engine approaches stoichiometry naturally. This is the point where the engine runs most efficiently (the laws of conservation of energy state this). For a transmission, though, it means that the revving engine will put added strain on clutch packs, bands and gears and, as such, it can cause premature wear so that an transmission that should easily last until 120,000 miles without major work, may find that at 85,000 miles the work needs to be done.
As your Suzuki is at 83,000 and is exhibiting troubles that can be linked to worn clutch packs and bands or problems with the valve body or even torque converter issues, it is likely that it is just experiencing premature transmission wear. It is possible that you may be able to save things with a rebuild in place, though, you should be ready to accept the fact that your transmission could be gone and that you are facing major repair bills.