and both said we wanted children in the future, probably not until our mid thirties
OP, you are very uneducated about fertility if you thought a good time to start was probably not until your mid 30s. Plenty of women do have healthy babies and conceive at that age, and later than that too, but it's definitely not something anyone should actually plan to do if they can avoid it. I could sort of understand it if you both said late 20s or 30s, but not mid 30s.
It very risky for you to stay with him. Please don't be like women I've seen on here who waited around for their partner, only for their partner to leave them for a younger model at the tail end of their fertility between the age of 33 - 43. Their boyfriends or husbands keep leading them on, breadcrumbing them saying things like 'next year when we have more savings' or 'not right now it's really busy at work'.
It's really important that he's enthusiastically onboard with having children.
Also, I wanted to add that I'm a non-religious millennial who cares about women's rights, so please bear with me when I say this, but I note that you've been with him for a long time now and you're still not married. I wasn't either, and I was also not bothered about, nor was I going to be one of those women who have to push their partners into it or beg for a proposal.
However, even though proposals don't necessarily lead to a happy or lasting relationship, I learnt over time that many people won't marry unless they're absolutely sure about their partner and committing to them. It's how men are picky - they will happily co-habit with a woman for years, (sometimes will even have children with her if that is something the man wants) ,but won't marry their partner because that partner is a 'just for now' person. They shut down conversations about marriage by being silent or unenthusiastic, or demean her needs by saying things like 'it's just a piece of paper'. In reality, they're secretly waiting for someone better, 'The One'. Simply put, they're just not that into you.
These men will test you further and further over time with how little they can get away with giving you or committing to this relationship. He already knows that you have stuck around this long without getting married, that you have uprooted your life for him, and now I wouldn't be surprised if he's seeing if he can get you to hang around for another decade, childless, whilst he makes up his mind or until another woman arrives on the scene.
This is a very difficult thing to accept when you love your partner, they seem an otherwise nice person, but many find this out the hard way.