You know if you're doing a good job or not, and you should trust yourself and not let these people make you doubt yourself.

I had a similar situation in which I had been hired for a job and went absolutely above and beyond the call of duty, and I was actually fired because they said I was a "slow learner".

Now - I know for a fact that's not true because I've been rapidly promoted to the highest point possible in every position I've held before and since.

I found out later that the reason they'd fired me is because they thought I had noticed their medicare fraud and they were afraid I was going to turn them in. They fired me so that they could say it was a disgruntled employee thing. I hadn't even realized what they were doing was illegal.

So - I realized that employers often have hidden motives for the things they say and do, and that they're not to be trusted!

If you're working in a snake pit, pack your things and move on before they bring you down to their level. You're better than that.