Low sex drive..

I'm a little confused, and actually quite upset about this and I've been telling myself for months now that it's ok, and that I don't need sex etc... but I would really like others opinions..

My husband and I have been married for just over a year now, and since our honeymoon, his sex drive has seriously decreased. He doesn't seem interested, and it's usually me who has to instigate something, sometimes with it failing even after having put something sexy on and really trying.

The times we do end up having sex, which is generally around 2 or 3 times a month.. it doesn't last very long and I'm offen left unsatisfied, and wanting more.

The times I've spoken to him about it, he says it's due to his weight gain since our wedding, or says something along the lines of being tired after work etc.. I can't help but feel like he's not attracted to me anymore (I too have gained a lot since our wedding).

I just don't really know what to do.. any advice?