with Mark, I am all about the sex, when I get it, GREAT, when not...well I do not feel loved by my wife.
Your biggest obstacle is communication, you both need to communicate better.
to what you want, he also has to understand not all women ahve high sex drives, your's is probably higher then most I would assume with 3-4 times a week, pretty good.
My wife and I have learned to spice things up, we dated for 7 years, married for 12. we will go on date nights and she will wear a sexy dress, or we will do other things that spice things up for us. We have three children so we are go go go with them and we hardly go out alone anymore, but you need to do that every so often, just a fun night as a couple.
We also do role playing, read erotic novels together, some 'adult" board games, etc. While it is not for everyone, it works for us.
But you both sound like a lovely couple, I wish you the best, just have some fun with marriage, you can do things with your husband that you can't do with anyone else...have fun with it.