If I could get on my knees and beg you not to move in with him I would. You say it is an otherwise great relationship, but you may be a bit lovestruck and missing some things. At any rate, the things he is doing to you are abuse in my opinion.
I don't mean to be harsh but here is how it reads to me. From what I read of what you posted he sounds very controlling, abusive, and narcissistic. Here is an example to give you a comparison. When I found out I had celiac my husband INSISTED the entire house go gluten free. He busted his butt learning about CC, how to handle it and what to do in the house. When he found out our son also had it, he became vigilant.
He never ever questioned me about my food. As a matter of fact he will err on the side of caution and if there is something I am willing to eat that HE feels is unsafe, he will ask me not to eat it. HE will ask ME not to make my own self sick because he is so worried about me and it gives him pain to see me suffer.
One time he was starving after working a 10 hour day and commuting for 2 hours in traffic. I had not made dinner. Kids and I ate out. So he grabbed a quick teriyaki bowl at a local place and brought it home. My son was crying because teriyaki bowls were his favorite. My husband could not apologize enough and he has never once brought gluten into our home again.
Our home is a zero tolerance gluten free zone because of my husband. I was willing to try a shared kitchen and he was adamantly against it.
If all he was doing was arguing over the blender I wouldn't think it was that bad. But the man is arguing with you to the point that you feel so incredibly harassed and beaten down that you are eating gluten and making yourself sick in order to avoid a fight with him.
Do you see how that sounds? Pretend that you are your own mother and you're hearing that some dude is treating your daughter that way. What would you tell her?
My last piece of advice is don't shack up with anybody. The odds go way up that you will not get married and if you marry your chances of divorce are significantly higher than if you had not shacked up. When you shack up with someone, it's generally because deep down in your core you have doubts about marrying them, so you rationalize that you are saving money, getting to know each other, etc. I have been divorced when I was younger from my first husband (who reminds me A LOT of your boyfriend) and I have broken up with a boyfriend I was living with. Both of them were equally hard and equally traumatic. I wanted to break up with that guy for two long years but because we were livng together I could not extricate myself from him financially. It cost me more money to break up with the live in boyfriend than it did to get my divorce because of how we handled our finances.
This guy has so many huge red flags, I would run screaming like my hair is on fire and never look back. It will only get worse when you live with him or God forbid marry him.