TL;DR: Boyfriend of almost 3 years keeps doubting my words even after I've said in no uncertain terms that he shouldn't doubt me, he says he doesn't doubt me but will then fight me over something I say that makes him doubt me. I think it's because of past trauma and some of our different views in life, but we've already worked through it. How do I understand why is he doubting me? How do I help him understand my side?
I need some third-party who can shine a light on this. I am unable to understand this behaviour.

Background:

I am an actress, have a twisted personality because of this, and I am a very manipulative person. My bf is also very manipulative. We are not bad people, please do not think of the word manipulative as in abusive, on the contrary, it became a defense mechanism because of stuff that happened in our pasts.This leads to both of us double or triple think EVERYTHING that is said to us and also makes us double and triple think EVERYTHING we say. It's mentally exhausting.Knowing this, we sort of made a pact that between us there will not be any double thinking or hidden intentions in what we say to each other, and it was working amazingly once we grasped the concept of "not everyone is out to get me and hurt me so I dont have to protect myself".

However our personalities crash, we love each other so much, never had problems outside of misunderstandings due to what I stated above that sometimes the other says something with no hidden intentions and the other one believes there's a hidden intention. We've worked through all of our clashes and are now in a place where while our personalities still are very different, we can understand each other and avoid all conflicts and misunderstandings.

I think all of this details are important.

My issue:He still believes I am not invested in our relationship. He says, and I quote, he's "afraid of me secretly wanting to pursue other interests and that he's limiting me, and that there might come a day that he will be an obstacle in what I want to achieve"This is not a first, I can vividly remember at LEAST 8 times we've fought over this, all of those in which I've assured him that is not the case, that my future plans involve him, he says he understands, and then months later I will say something related to my view of life - which is "when that happens to me, I will think about how to solve it, until then, I won't think about it" - and he will inmediately start doubting me and saying I am not think of him in my future or that he's afraid I will ditch him if something major happens that requires leaving him.

This line of thinking comes mostly because I, as an actress, do not see a problem with romantic scenes and he does. He believes if I have to kiss someone on stage is cheating and doesn't tolerate it. I do not share that view, but I respect his boundaries and agree that, I personally wouldn't feel comfortable and would be grossed out by acting romantic scenes while in a relationship (if I was single, I would be ok with it). However, I also told him that my marketing profile is not one of a person who will ever do a kiss scene.

I do not fit the role of a girl who will be kissing or having sex on screen/on scene. I know what sells and what people like to see, and it is not me. I know I will never be paid or cast to do that, so I don't see it as a possible obstacle in my relationship. He understands this, but says he's still afraid of him "getting in my way" if I ever get offered a role that demands too much of me.

I also think this sort of have to do with me being his first serious relationship. The other two girlfriends he's had lasted around 3 months, one of them I think got close to the year but they broke up because she cheated, and he cheated back in revenge. He denies it, but I feel there's still some trauma left.

Another thing I think influences his doubts is that I'm childfree and against marriage, he wants to have a wedding and a kid. We sort of compromised that right now, at our age and considering a lot of problems we have to deal with, there's no point in thinking about it because we are not close to a point in our lives in which the decision of a family and a wedding is important.

I've told him, repeatedly, in multiple occasion, in no uncertain terms, how much I love him and plan to stay with him for the rest of my life. He still is afraid of the future. Is there something deeper he might be refusing to tell me? How can I understand his point of view? What do I do?

English is not my first language, I'm sorry for any typos or grammar errors.