I agree with the first answer about a trial run (living together) and see how it goes. It's normal to question the relationship now and then because all relationships have their up's and down's; it's just a question of the both of you being fully committed to listening to each other, communicating, supporting each other etc when problems arise.
After having four relationships two of them failed completely because those two men weren't interested in dealing with problems in an encouraging way. They always had to be right and score many points against me... completely unhealthy. But as you've said he's been supportive it sounds like it's a "go" to me.
You said you can't imagine your life without him, which is good so tell him this and maybe ask him the blunt question and see what he says? Depending on how he answers you, the answer might be crystal clear. It might hurt, it might be puzzling or it might be the sweetest answer you've ever had... but then at least you'll be clear on where you stand.
As for long distance, personally I would find this very stressful, upsetting and draining. Even if I was in a long distance relationship and I thought he was the one, I'd have to let it go eventually especially if it's going to stay long distance. If it was meant to be things would become easy and one of us would make a serious move - but if not there's something wrong (or some hesitancy there). You really need to look after yourself at the end of the day.
Hope this helped :-)
Oh sorry, I obviously said a bit too much :-)
Suggest trial run living together, 6 months to two years.
No better way to get to know someone really well.
Does require huge upheaval because one of you has to move.
Yours to decide whether the risk is worth the effort.
Sometimes people choose long distance lovers precisely because the separation provides a safety shield against too much closeness, feeling smothered or trapped.
It doesn't hurt to look inside a bit, to see what's really going on.
If the prospect of living together makes you nervous, that would be a good clue.
He says if it was so easy for me to let go I probably didn't love him from the start and he calls me weak for not trying to patch things up but truth is I am strong for finally letting go .