너 진짜 사랑해 sounds so weird... And both of 나 너 진짜 사랑해 and 나 너 정말 사랑해 sound a bit awkward to me.
If I were you, I'd like to say 진심으로 사랑해 or 내 온 마음을 다해 널 사랑해. These two express the essential meaning of what you suggested first. Besides, they don't sound lyrics-ish or excessive. Just really romantic.