Ear training question

I've a question about that thing musicians don't like to talk about that is ear training! When listening to music, I'm quite good at being able to play the right notes in musical phrases after I hear them without use of trail and error. But even though I always get it right, I'm very slow at it. I'd be good at transcribing, but not playing, if you get me. Something is't quite right... I still can't really play what I hear in my head without thinking about it. When I don't 'think about it' yes I do find that my hand will reach for the right notes; but sometimes it will go a mile in the wrong direction! This is a concern for me, as I've been playing a long while!

I've tried a different form of ear training recently. Something that is sort of the opposite of what I've been doing all along. And that's trying to sing notes (that I look at) before playing them. So I'll start by playing just one note, and then I'll look at a bunch of other notes after that note; lets say and arpeggio, or the first few notes of a scale. I'll then try sing these notes! Will this help my brain interpret the piano differently? I'm absolutely useless at it btw! I've some sort of a mental block it seems. Other sounds just get stuck in my head and then I can't seems to sing any other notes but those ones. Of course I know the moment I sing them that they're the wrong notes. But when I try to raise the pitch of my voice to the correct note, I often can't seem to get it up, and I'll end up sing the same note in falsetto... or else I'll end up going a whole octave higher.

I can manage to sing the notes I choose to look at if I imagine a known reference point before singing any given interval. Like 'Here comes the Bride' for a perfect fourth for example. But that's sort of cheating. I should be able to sing notes that I look at without imaging such reference points.