Hi Beauchamp! You might like to hear this...I felt like a failure because DS2 didn't take a pacifier! We are awfully hard on ourselves for SO many reasons!
I just have a moment, but whether you truly have PPD or not...give yourself credit for having an extremely exhausting job and you are doing it on so little sleep! The early months of parenting are BY FAR the hardest parenting I have lived through (I have a 16 year old, too, so that's saying something).
I hear you on loving co-sleeping but it hurting...we sleep with our almost 17 month old, and I wake up sore a lot from weird night positions, night nursing, etc.
Do you have any mom friends, LLL group access, etc.? Any family that could be of help (some family "help" isn't very helpful, I know)? Getting out of the house, social contact of some kind and taking walks helped me a whole lot with my PPD. I was also "lucky" enough to have a DH who was unemployed for a time after our LO was born and he was so helpful with FOOD. I didn't need help with the baby. I needed food and sleep. I also needed, frankly, a cheerleader to tell me I was a good mom since I felt so rotten all the time.
I found the early months of parenting a newborn to be very isolating and depressing in many ways, plus it is physically exhausting. Remember that any other job where a person is on call (unpaid, of course) 24/7 would be unheard of, right? So why do we expect it to be so blissful? IT IS HARD!
Gotta go...toddler on the loose. PM me if you'd like...I hope things are easing up a bit for you!