Based on what do you suggest easyjet discriminates you?
Everything you describe is different times to the same person, which is normal of course.
It can also always be that when you search for a fare and start going through the booking process, this seat is removed from general availability for X minutes/hours, so if you search again 5 minutes later... it will not be there.
There are some people who suggest deleting browser cookies might help reducing the price in some OTAs, maybe it is also the case with easyjet.