After sleeping for the first 72 hours to become a vampire. For some reason my vampirism won't go up. I've slept for 4 days and it's still at 25...

Have you fed? If you have it's a glitch, if not try without feeding.

It takes a long time I've noticed for me it took longer than the guy said I just kept sleeping until I seen it go up.

Ok ya I fed and it still stayed at 25. Also I've tried after waiting the 3 days to just play the game and see what happens. It finally went up to 100 but when I feed even if I wait a couple days more it goes back down to 25. Oh and when I wait the couple days I'm playing the game and it stays at 100.

Is there a console command to make it stay at 100 and think I've fed to become a full vamp?

Here's the thing- feeding doesn't make your Vampirism level go up, it makes it go down.

http://www.uesp.net/wiki/Oblivion:Vampirism#Advancing_Through_Stages_Of_Vampirism

Ah ok I thought it was that you had to wait 3-4 days then feed and you stay 100% vampire. So if I wanted I could feed then it raises if I don't feed for awhile again?

Yup, thats the unique ability of the cyrodiilic vampires. Read the book http://www.uesp.net/wiki/Lore:Immortal_Blood if you want more info.

Your right that book was very insightful. Too bad for the ending though lmao.