I worked at a practice where I stayed 7 years. Started on reception then trained as a dental nurse ( big deal for me since I was 50!). Since I was a conscientious worker, even when I was training and had college work etc, I was doing the same as you, medical emergency kit, stock ordering, training other trainees! I was always requested by the dentists so never got a quieter day. Always went in early in my own time to ensure all set up correctly and was stocked up etc, and often ended up setting up extra surgeries for late staff!
So unfortunately you are not alone.....
HOWEVER..... this experience has been used to my advantage, because a year on from qualifying and having been made lead nurse.... I resigned and moved to a practice as assistant manager, I still nurse and cover reception when needed, but they appreciate my skills and they thank me, yes I said thank me!!!!!
I also get paid a fair wage.
I hadn't realised the affect all this was having on me till I left and suddenly felt like a huge weight had been taken off my shoulders. I also realised how valuable I was, to the right practice.
Write yourself a CV, detailing everything you do and are capable of.... get it in circulation, even ask some other practices if you can go and shadow a nurse there for a morning to see what other practices are like, I did this and got offered 2 jobs.... it also gives you a feel for what other practices are like.
Everyone deserves some appreciation and thanks, and there are practices out there, however busy, that have these skills on how to treat their staff and make them feel valued.
Only you can decide how long you want to carry on working in this environment, but you sound like you have a lot of very transferable skills.
Good Luck , whatever you decide to do.