I have 100 enchanting skill w 5/5 enchanting perks yet when I try to enchant something the enchant gets weaker,
example: if i wanted to use the fortify one handed enchant when i select it it goes from 13% to like 6% decreasing instead of increasing as it should....
So is there a reason for this? is it fixable? or am i screwed and have to start over?

I think it depends on what soul gems you have and are using for that enchantment. Grand Soul gems are the ones I use and it is always above what the first percent was.

The soul gems(+souls) you are using will determine the power.
The initial value it gives might be for the highest soul gem you have so it will drop if you use one that is lower.

However if you are seeing this drop while selecting a black or grand gem (with grand soul) then you might have a problem.

When you are first looking at the enchant, but not actually selected it yet, from the list the value it shows assumes the best soul gem in your inventory without perks factored in. This is not the case if you have selected the soul gem first.