Uncertainty in relationship. Ticking biological clock.

I have been married for over a year and although there is a whole lot of love in our relationship, I am not in control of the thoughts and story I’m telling myself about moving forward and trying for children with him and it has affected my mood and sleep over the last year.
The story I am telling myself is a mixed one of overwhelming love and respect for my partner and then a polarising thought of whether I feel right about him to be the father of my children. He would make a great father, I know that. I haven’t worked on my thoughts enough yet and wondering about trying to change my narrative or am I just lying to myself?
We are moving to IVF next and I have taken a break to gather perspective and sort my head out as it is unfair to him at present and I feel a lot of shame around these thoughts.
I am wondering about whether the story is one of self sabotage and fear of moving forward and being happy or whether my gut is finally talking to me.
Any advice would be much appreciated.