I had the same problem with my libido while I was breastfeeding my younger son. All day long I had these 2 little boys clinging to, climbing on, or just needing me. It can be taxing. Then add breastfeeding on top of that and you begin to feel like your body isn't yours anymore. My husband used to get offended when he'd come home from work and want to cuddle but all I wanted to do was leave the room for a while to clear my head and not be touched by anyone. After the kids were asleep, he'd try to coax me into wanting sex but I just couldn't get into it. Like you, I never flat out refused, but I just felt no desire whatsoever which in turn frustrated him. I breastfed for a year so you can imagine how bummed my husband must have been!
Once I weaned the baby, my libido came back full-force and we became much more active in the bedroom. I think it helped that once I was done with breastfeeding, I was able to lose weight a lot more easily which helped my body image. (I was not one of the lucky women that breastfeeding helped to lose the baby weight.) It has also helped tremendously that I make a conscious effort to get in a little exercise a few mornings a week. Even though it means I have to get up an hour before my kids, just 30 minutes of brisk walking on the treadmill and some ab crunches boost my energy and I feel better about myself.
You need and DESERVE a break at least once a week. I think men tend to misunderstand what it means to be a stay-at-home mom. Yes, we can choose not to wear makeup or wear pj's all day, but it's not like we sit around on the couch eating chocolate and watching soap operas all day. Raising children is work. If you get some time to relax, you may be more apt to want attention from your husband. Ask him to watch the girls while you take an afternoon to yourself to do whatever you want. At first it might feel strange to leave the house without kids in tow, but there's also a sense of freedom. I've found that getting a pedicure while reading a magazine is very relaxing. Maybe meet with a friend for a lunch date and some good conversation. Maybe you could shop for a few new clothing items or undergarments that make you feel good about yourself and the way you look. Sometimes, it's nice just to go to the grocery store by myself! Just know that you're not alone and things will get better. Explain to your husband why you're feeling this way and try not to get down on yourself about the situation. Hopefully he'll understand and respect your needs. I hope this helps. :)