I basically could have written your post. I have a 16 month old, and he barely eats any solids. Like you said, the random cracker here and there. He is definitely teething, so I think that plays a major factor in it. It's hard when solids seem to be a milestone in our culture, and all the babies you know are devouring everything. I tend to compare and doubt everything anyway, so this has made me feel a little nutty.
Then, yesterday I decided I'm going to just let it go. Trust that whatever is going on will work itself out, know that breastmilk is highly nutritious, and follow my DS's cues. I still offer him food, try to make him smoothies, and eat well myself (as well as multivitamin, fish oil, probiotics). The night nursing is tough. I try to nurse him lots before he goes to sleep for the night, and sometimes that helps, but he still wakes at least 2-3 times. Again, it's hard when mama friends are snoozing so well at night, and here I am nursing just like the newborn days. The main thing that gets me through is that it won't be like this forever. This is just a short span in the big picture. I try to nap when he does, and go to bed when he does too. Is it convenient ? Not really, but I don't think parenting always is !
I'm sorry this has become long, but I feel for you, mama. Take care of yourself ! You're not alone. Try not to compare yourself to what is considered "normal", because that's not always what is best anyway.
Don't you wish you could just look into a crystal ball, and see that 6 months down the road everything was fine and worked out ?