Your DH is right about you knowing. You will know your child better than anyone else. You will be the expert. There are major milestones, but these are guides and children do it at different stages, and this is nothing to do with how bright they are, how good a parent you are etc.
They tend to roll at around 4 months, sit around 6, walk around 1 year. Some crawl, some bum shuffle, some just get on their feet and cruise before walking. Obviously if a child is way out on these, there may be an issue. As a parent you would probably know this, and the HV would hopefully pick up on it.
With regards to sleep, they all like different things. One of mine hated being swaddled, the other could not sleep without it. I swear by gro bags, but others prefer blankets etc.
Thankfully they develop fairly slowly, but you will find once you are used to one stage, they will be moving onto the next.