Oh I really feel for you OP!
I was with my ex fiance for 9 years. He proposed after 8 years together.
Around 4 years before we got engaged, I reached a point of certainty about him and also wanted to start a family (I was around 30.) I sat him down several times for a serious "look, I want these things and need to know if we are on the same page" chat, and every time he would run rings round me with a variety of excuses and delay tactics, everything from "I am absolutely going to ask you but I am old fashioned and want to do a proper proposal" to "well I had he proposal all planned but now you have ruined it" then his Dad sadly died and it became "my mother is all alone now I just can't do it to her, it would be too much for her to bear..."
I consider myself intelligent, driven, a feminist. I am not passive in my life but in this situation I felt completely powerless: I was so in love with him, certain of what I wanted, and left feeling humiliated and hurt every time he delayed, but he was also so convincing that he loved me, that I just had to be patient, that it really was important to him...and I waited.
When he finally did propose, it felt...flat. He'd dropped hints that my birthday present that year was a ring. Then my birthday came and went, and nothing. I was so fed up, started thinking about leaving. Not because I wanted a fancy wedding, but because I felt so rejected and deceived. Then he proposed the next day. I buried the now-obvious reality that he had realised he'd pushed it a bit too far and just didn't want to lose me.
He seemed excited about the wedding though, and even wanted to arrange a second wedding in his home country. But as the wedding got closer he became avoidant and depressed: he hadn't organised anything he'd insisted on taking responsibility for (the music, the food, his mother's flight...) and snapped at me whenever I talked about the wedding.
A month before the wedding, I sat him down and asked what was going on, did he have cold feet? In response he accused me of cheating on him out of the blue (I had not) and said we had to postpone the wedding until he could be sure he could trust me.
At that point I finally came to my senses and left him.
It is now over three years later and he still tells everyone I practically jilted him at the altar and broke his heart!
I am now with someone lovely who will openly discuss the future with me like a grown up.
I suppose I am sharing this to reassure you that it is so easy to get caught up in situations like these, and I completely understand. It's very easy from the outside to say "oh ffs just ask him don't be so wet" etc but men like this can be so manipulative, giving you just enough to string you along. And you can get lost in the fog of hurt and desperately not wanting to seem desperate.
It will hurt, but you really should get out. Even if he does finally propose, it will likely feel a bit hollow. As others have said, you deserve to be with someone who cannot wait to marry you and is excited at the prospect!
I really wish you all the best 