Hello Kayleigh. Remember me?
I see you are still worrying about these headaches. The floaters are normal for a start. I have floaters. I remember being as young as 12 having floaters. They keep getting worse and worse. That's what they do. You learn to deal with them and you barely notice them anyway until you start thinking about them. Secondly, the blue flashes can definitely be linked to your anxiety. I was having flashes when I was worrying about headaches. They are common with people who suffer from anxiety. Do they appear at the corner of your eyes? Do you wonder if you saw something real or whether it was just your mind? Because this was common when I was having them.
Now, on to your brain tumour fear: if you do have a brain tumour, and if you have had it for 3 years, you would be having seizures by now. Not only that, but 3 years of cancer would almost definitely be clear not only to yourself, but with everyone who knows you - they would notice the changes. Brain tumours can effect your personality as well (depending on where it is) as well as your memory, cognitive ability etc.
You also said that you went a year without them. An headache caused by a brain tumour DOES NOT come and go. It progressively gets worse due to increasing intracranial pressure. The brain tumour itself doesn't cause pain - it is the pressure the brain tumour causes between the brain and skull. And as you can guess, the tumour would of had to grown significantly in order to increase the intracranial pressure although it is of course relative.
My bets are still that your symptoms, and also your problem, is with your anxiety and NOT a brain tumour.
Have you gone through any measures in order to overcome your anxiety? Or are you still worrying for the majority of your days? Because I am guessing that this worry is really exhausting for you?