@Mum84762002 I would say give yourself time, if you can.
I have three and at the stage you are at I was going through a lot of the same thoughts - sad at the passing of stages, wishing for another, But also struggling. 1 and 3 is a very hard stage, physically and mentally.
DH and I weren't sure we could cope with more, we agreed to leave it and discuss again in a year. Then another year. Eventually we had a third, which was the right decision for us. And the time meant I had processed much of the 'baby grief', so it was a decision made by me and DH for our family not for my feelings, if that makes sense.
I found things a lot easier with a bigger age gap - something which many on Mumsnet feel is wrong/unfair. But it has so far been right for us, and it was good for me and my siblings. There are challenges with three - logistics, mostly, and how to balance everyone's emotional needs. But I feel I am more confident as a mother so it balances out. My DH and I have always had a strong marriage, we love being a team amid the chaos of family life even when we find the logistics tough.
It's helpful to share your feelings with strangers as you can talk openly etc. But really we are all strangers and we don't know what is right for you. What you are feeling is normal and valid,but whatever happens, You don't have to decide right now what your family will look like for ever.