Just popping in to offer some support and a message of hope!
DS was a decent sleeper as a newborn - up every 3 or 4 hours for a feed.
Then at 3.5 months things went totally pearshaped - after that, he woke every 20 to 45 mins unless he was sleeping on one of us. This went on for 2 months-ish, until suddenly just before he was 6 months, he just started sleeping better. He would regularly go 3, 4-hour stretches.
I think this was classic sleep regression - we couldn't work out what caused it, nothing we tried would change it and and I don't know why it ended.
While we were in it, it was horrific, and I feel for you all. But It Will Pass. Hang in there.
Also, DS who is now 7.5 months has recently started sleeping through (ie 7 til 11 dreamfeed, then 11 til 6/7) - we did CC with him, and I am about to start a separate thread to say what worked for us and why.
Good luck all. You WILL get there. Keep the faith...