I don't think you can really make this distinction. Because, the effect of using your muscles can sometimes only be seen after some delay.
The chemical reactions involved in muscle contraction are very complex and involve multiple proteins and regulatory cycles.
It may also be related to other factors, such as how much protein you had in your food.

For instance, in MuSK MG (which I am not saying you have), the antibodies interfere with signaling pathways (as opposed to what happens in classical AchR MG were they destroy the receptors). This causes abnormalities and instability in the assembly of the NMJ (even if there is an adequate number of receptors), abnormalities in the function of acetyl-choline esterase, and possibly other abnormalities (including in muscle energy production).

So, the effect of exercise may only be seen after a few hours of even days.

I believe that this misconception regarding the immediate effect of exercise is one of the reasons that so many patients with myasthenic syndromes are not diagnosed properly or that some of their symptoms are not seen as related to their illness.

I think it may be also the reason that patients fail to recognize the relation between over-exertion and exacerbation of their illness. ( I know it was so for me, until I gradually realized that things are much more complex than they seem).

I think that there is classical AchR MG which has a relatively simple mechanism and many other much more complex and less easy to understand myasthenic syndromes. And from the way you describe your illness you have one of them.