Oh how frustrating for you. It's perfectly normal to go off sex after having had a baby, even for so long. Sex for us was completely different after baby, and certainly didin't resume for longer than either of us would have wished.
It's really unlucky that your dp has a one-track view of sex. Men turn on so easily that they don't seem to realise that women don't necessarily do so as well. What's more, the less they have the more they want it and the faster they turn on (BTW, I may be making sweeping statements here, I'm not hugely experienced, so feel free to shoot me down), whereas IME I get out of the habit if I don't have much sex. My head may want it, but my body doesn't necessarily cooperate.
Something which worked for me - but requires the full understanding and cooperation of the parnter - was to have an agreement that we would not have sex. Let the cuddlign go further and further each time, get more and more intimate, more heavy-petting teenagerish over a fairly long period. Not a specified period, but completely open-ended, weeks or even months. But never get to complete sex, not even getting him off. (If he feels frustrated by this, well he'll have to go visit Mrs Palm in the bathroom, because at this point you're not doing it.)
The lack of pressure on you to 'perform', and the lack of apprehension over whether you are going to go all the way, is very relaxing, and gradually each time gets more and more exciting, until eventually you initiate the next stage, whatever you want it to be. And when you finally get roudn to doing the whole business, you want it.
I also second the suggestion of baths together. Lots of gentle, delicate intimacy.
Another point is that you may be run down - 8m is still a very young baby and hard work. Try taking a good multivitamina nd mineral supplement to help boost you.