Hi you've had some really great advice here - and I too initally thought you hadn't had sex in 3 years and thought eeep!
You might want to think about "scheduling" sex - either a date night (not a big fan of that term) or even pop it into your mental diary - i.e. "7AM april 12 - jump DH's bones."
(note if you go with a regular date, you might want to drop some hints that some romance would be appreciated)
This might help you feel more "in control", rather than doing something to please your husband - which might make you more interested in it!
On a more serious note, while what you've described about your sex drive and frequency does not sound really unusual (down the tail end of the normal range admittedly), if you or DH think theres a problem, you might want to think about what has caused your loss of libido e.g.
Tiredness
The endless grabbiness of small children
Unhappiness with your bodyshape (though your husband thinks you're beautiful I bet!)
Identity issues - having difficulty switching from mum to wife
etc.
While some of these will simply pass in time, others can be 'worked on'
In any case big hand to you and your DH for talking about it! It can be hard - but as you have seen, it can make it simply something for the two of you to work though.
Good luck!