Hi OP, I'm really sorry that you're going through this - it sounds terribly stressful and my heart really goes out to you.
I've been with my DH for 20 years now, married for 10, and my advice to you and your OH is: for now, forget the wedding.
To make a long-term committed relationship work and be happy, you need to have a foundation of trust, communication and consideration for each other.
My red flags in your situation are that all this is in a mess right now. Having nerves/doubts is normal, but why didn't this get resolved in a deep chat and some mutually agreed compromises?
Why did he string you along for so long agreeing to things he didn't want? Does he feel unable to be honest? Is he trying to make you happy by being something that he's not?
There are endless, endless challenges in a marriage, some huge, some tiny. They all need to be resolved if you're going to build a happy life together. Think of this as the first big test and see if the two of you have what it takes to find a loving way forward?
If you can, get some couple's counselling before you decide what to do. But if he won't do that, with all the stakes as high as they are, then I think you should walk away.
Better now than after you're married/have kids together. You deserve someone who will be honest with you, that's the long and short of it. 