If your question is: can you have MG with a negative antibody test (I assume you only had the AchR test), the answer is: yes.
About 20% of MG patients will not have detectable antibodies on this test.

Some will end up having another type of myasthenia: MuSK

Some will have AchR antibodies which will be detected on a more sensitive test.

Some will have antibodies which it is not yet clear if they do or do not cause myasthenia such as LRP4 or anti-ryanodine.

And some will have no detectable antibodies with all the currently available tests.

This does not mean that you have MG, it just means that it is still a viable possibility, if there is no other more reasonable explanation for your symptoms.