If he hasn't requested that you not contact him, I think there's no harm in sharing your feelings. Telling someone that you love and care about and would like the chance to get to know them better or to be with them someday is not the same as DEMANDING that they be with you. Maybe right now, you aren't ready for a relationship with them, or vice versa, or both, but maybe you are. And maybe, even if you aren't ready right now, those words will still have proven valuable in the future. Maybe he will remember that you said this, and it will help him in a moment when he truly needs hope or courage, and maybe that's when he'll come to you.
I guess what I'm really trying to say is: unconditional love doesn't hurt. If your intentions are genuinely about unconditional love, don't doubt yourself. Love might have its own timeline and its own path, and it's good that we recognize and respect this.... but we don't get in its way by expressing it. If anything, we help to clear the path for it.
Healing is ultimately about removing the obstacles within our hearts that we have built against love. Expressing love seems like a very clear step in that direction. ;) The less you dam up the love that you feel — the more space you make for love to flow in your life — the more magic it can work.
Drop expectations, let your heart speak, and then trust that love will do what its divine wisdom would have it do.
Wishing you and your twin flame many blessings.