Soo i started off using Eve as an Ap then now im switching to AD but which one is better?

I only finish my built once for AD
and it was

boots of mobi
triforce
ghost blade
wriggle lattern
banshee veil
hextech gunblade
+ all 3 elixer.

During late game, i can hardly kill anyone without my teams help.
My E does a lot of damage but spamming Q and auto attack hardly kills/ damages them at all. My attack was around 250-300 ish

Soo can anyone help me with my build?

Well it's not clearcut which one is "better" because there are both pros/cons to both builds but AP is more team dependant as her role is more fixed usually. AD performs better generally speaking so in that sense she is better.

My experience is the exact opposite as yours. I start out with Lantern and Boots and at this point my damage is suboptimal. But once I get my Tri-Force and Ghostblade I pretty much have what I need to tear just about anyone to shreds. Pop 'R' and activate Ghostblade and like a blender i eat them.

well, the only time i actually do damage is against ppl like ash and teemo when their hp are really low, besides that. I barely do that much damage,

If you are used to playing AP eve I might suspect you are used to the insane burst from Ravage and Lich Bane proc. AD eve does not have that but you deal more damage over time as you hammer away with the occasional crits. If you go toe to toe with well geared tanks on full HP then no wonder you might get disappointed.
Sounds to me like you are running through the game under farmed compared to the average players. That is the only way I can make sense of what you experience as I've said I have a very different experience.

I dont go head on with a full time tank, I usually find ppl can pick with my team or ppl with low hp like ashe and teemo and those ppl with hp less than 2.3k or 2k.

Eve is an incredibly item-dependent hero, I find, so you HAVE to ensure that you either get farmed or get kills. If it doesn't look like you can get kills, then you need to focus on farming. That said, I am not an expert on Eve, but I prefer to build her with Trinity Force, either Sorcerer's Shoes or Merc Treads, depending on how I feel, then go for Bloodrazors. Her ult has HIGH attack speed bonus, so you'll rip apart anyone who you open up on. Throw in some lifesteal to build into a bloodthirster, and then an infinity edge if the game goes on, and you'll be fairly powerful.

There are at least 2 decent threads about this in just the top few pages.... come on now.

I had some successful DPS eve moments.

If possible, just go jungle.

My items usually are

Shoe (depending on the other team)
Madreds Bloodrazor
Bloodthirster
Black Cleaver
Starks
and game ended before my 6th, and my opt would be either GA or banshees.