Everything you just said is exactly what I have been going through for 2 years now. It sucks! I have my good days and my bad days... just like everybody else. My vision suddenly decreased dramatically and thats what brought my fear of going blind or having a brain tumor, up. But went to 2 eye docs and my regular doctor and all said was fine, just needed a prescription change. The eye floaters are nothing. Everybody has them and they are harmless. The only time you should worry about them is if they are SO bad that you can't see, which is very rare. I noticed that the more I think about my floaters, the more that they appear and bother me. So try to ignore them. I get the pressure on my eyeballs too and it feels like sometimes my eyeballs actually hurt. But I notice that this only happens when I have a bad headache or didn't get much sleep the night before. My eyes are so bad at night. My eyes are really sensitive to any type of light at night time.
This is ALL anxiety. It is very rare to have a brain tumor and you would have more SERIOUS symptoms if you had a tumor. Just remember that tumors take years to develop, they don't just pop up.