Quote:
"Can someone go over this?? There's quite a few parts that confuse me..."
Good attempt
JunjouLover! But let me suggest that to avoid confusion, you read the entire text or sentence before you start translating, then you will understand the meaning/story behind the lyrics and translation will become much easier. Don't search for exact translation, ie: word per word because doing so, at times, will lose the entire meaning of the song. Also, don't translate line per line without paying attention to the entire sentence. For example: 'debes ser perfectamente lo que siempre sone' must be translated together and not in 2 separate parts because then the meaning will differ. Read on & you'll understand what I mean.
No pude descubrir - I failed to
realize/understand (in English & in this context, 'realize' is a more suitable verb than 'discover')
No me importó, ya que más da -
I didn't care, what does it matter now? (not sure about this expression)
Que yo probé tu desempeño en el amor -
that I tested your love commitment
Me aproveché de que habíamos tomado tanto -
I took advantage that we were drunk/had drunk a lot
Fuiste dejando y te agarré -
you were letting me (touch) and I grabbed/took you
A pesar de saber que estaba todo mal -
despite the fact that I knew it was all wrong
Lo continuamos hasta juntos terminar -
we didn't stop until we finished together
Te adoraría lo que dura la eternidad -
I would love you forever/for eternity
Debes ser perfecta para -
you ought to be perfect for (debes ser = ought to be/must be, not shall)
Como fue que de papel cambie -
how did my role change? (I think in this case 'papel' = role, ie: from boyfriend to lover)
eres mi amiga y ahora eres mi mujer -
you're my friend & now you're my lover (I think 'lover' is more suitable given their affair under the influence.

)
Debes ser perfectamente -
you must be exactly *
Lo que yo siempre soñé -
what I always dreamed of *
* As mentioned, the above 2 lines are connected in meaning, you cannot translate separately, thus 'exactly' and not 'perfectly'
Entonces el amor -
love then
Nos tiene de revés -
knows us inside out (not sure about this Spanish expression)
Seré tu eterna enamorada -
I'll be your everlasting love