Oi mother in laws... I would tell her that things are really fine, and that if you seemed stressed when you visit, it's because you are! Traveling with a 2 year old is hard, whether for a weekend or 2 weeks. You can give her all the reasons that being away form home is more challenging than being in the comfort of your own home and then add, " but family is really important to us, so we make the effort."
Maybe you could invite her to your house so she can see how things can be different. There's nothing worse than having to feel like you have to watch everything little thing you say and do because of what other people are thinking. It's really not any of her business. But I hear you when you say you respect her. In some ways though, it really is a different generation of thinking and a different time in life. When we see my husband's mom, I don't really care who moved out of the neighborhood or who died. I don't know any of those people and my husband hasn't seen them in 30 years. But it's something to gossip about...
I would listen to you husband. You both seem based in the reality that while your marriage may not be perfect, it's still good for you and you're happy.
Good luck!