Head space during fermentation

Hey everyone, glad to have become a part of the home brew community.

I'm currently using a 2 gallon wort that's fermenting in a 5 gallon container (no spout). I haven't seen signs of consistent bubbling through the airlock in about 4 days. All I see are a bunch of little non-moving bubbles in the airlock.

Are the 3 gallons of oxygen (head space) negatively interfering with the fermentation process and causing the air lock not to rapidly bubble? Or is this not necessarily a negative thing and the fermentation process will just take longer?

Or is there problem with the fermenting at all?

Thanks for the help!

Welcome! Also, odd place to post this question

1) Airlock bubbles are not a sign of fermentation. The only sure fire way of knowing if fermentation has started to ceased is to take a gravity reading. How long has it been in primary? Have you taken a gravity reading?

2) There is not going to be any oxygen in your headspace since the CO2 created during fermentation pushed it out and created a blanket of gas (CO2 is heavy.)