Hi,
Floaters are not abnormal at any age, though their frequency can increase with age. It appears you have very few anyway, as the Dr could not find them at today's exam. Don't worry about them.
It is good that the dr said everything is fine. I think you should trust his opinion in this case.
Please work on your overall health and anxiety. When you are feeling anxious about your health maybe you can do something productive like taking a walk, etc so you can stop thinking about it.