If you're happy, and he's happy, then it's normal. If no one's getting hurt and you're both satisfied, it's normal. But if one of you is dissatisfied, then you need to work on a compromise you can both be happy with. If one partner wants more, or one wants less, you probably would do best to try to find something in the middle. If one wants more AND one wants less, that's a little harder to fix. I'd suggest a sex therapist if nothing you try has worked, because I'm not one, and I don't know what to tell you, LOL!
In general, as far as passion goes, whether you're having a lot or a little, or in-between, or none at all, if you're both happy, then it's probably fine. However, if your libido is low (or his is), even if you're mentally fine with that, you should talk to your gynecologist to see if there's a physical reason. That certainly can happen. It can be for psychological reasons, too, and you should explore that, as well.
Marriage is work, and that includes the romance. Romance changes over time, but if you feel you're getting into a rut, work at it a little bit. Do something special for your husband, like hand the kids over to a babysitter for a night or a weekend, throw some rose petals around, put on some sexy lingerie, light some candles, and leave a note for your husband to follow the trail of rose petals...to you!
And he has to do romantic stuff like this from time to time for you, too, of course! It's not a one-way street!