我发现我拥有很多我以前不知道的天赋和才能在我体内.
不是的,句子这样来看
一句是I've discovered （that）I possess a large number of different talents and skills .
第二句是that （I never would have thought） were within me.
that指代的就是a large number of different talents and skills ,
“I never would have thought”是修饰限定that的.