I fed DS1 til he was 17 months. By that time we were down to the bedtime feed and I had just gotten pregnant, and he gave up himself.
My son was also lean, (he still is) all of the other babies in my mum and toddler group were chunkier.
Loads of mums here have bf way past 6 months. Good for you for feeding this long, and good for you for wanting to continue!