Should I see a doctor?

No, it’s not really necessary at this point. Most doctors don’t even recommend coming in unless/until u have completely skipped two or more periods in a row, since skipping a single period can happen sometimes & isn’t a cause for concern.

Most doctors won’t see you until 90 days without a period. There are many nonconerning reasons to miss a month.

They didn’t do anything for me unless I had missed 2 or 3 in a row.

So you skipped a period for October and have negative pregnancy tests? Absolutely you should be making an appointment with your gynecologist.