You have had an unusually hard time- it doesn't sound like a sob story.
My ds1 woke up a lot up to 7 mths and dh used to do the 730pm-1130pm shift so at least I'd start the night with a few hours under my belt. It did mean that ds1 has 1 bottle of formula a day, but it didn't seem to have an effect on my breastfeeding..
Have you had your baby's health checked-just to make sure she's not waking because of something like acid reflux?
My friend has her 3yr old in bed with her from about 11 each night-it seems to mean a better night sleep for them all.
I went the other way and did the sleep training thing-going in and shushing/patting his back but extending the periods between doing that. It mean't that ds1 started sleeping for extended periods and got a good 2 hr nap in the day too.
Is your dp on side with you? If you have no other support then you need to be a team.
Naps can be disruptive, but then you have to adjust your lives for a baby in some way. Does she fall asleep in the car? We used to travel at nap times.
Sorry if you've thought of all of this already.
Is your medication working for you? It can be hard to think straight with valium on top of no sleep.
Can you afford to pay for any help-my friend's little boy never slept and she ended up getting a childminder twice a week for a morning session-she would then just sleep. Or when I had newborn twins and a 2 yrold and was struggling the health visitor organized a voluntary woman to come for 2 hrs a week and give me as break.
You sound like you really need a break to me.