Looking for advice/reassurance!!!

Trying to break my seven month old from nursing to sleep - Sleep training was a complete disaster. My older daughter we let fuss for a few minutes and she went in the crib from day 1. My younger one is much more sensitive and she already cries A LOT. Always has, which is why I have been putting off sleep training.

At first she nursed to sleep and from 3 weeks old - 4 months old she would sleep 8 - 12 hours! Now her sleep has devolved , she wants to nurse all night and I'm so tired.

I tried the sleep sense method, started putting her in the crib with me there comforting her, she screamed for an hour at bedtime, then 2 hours in the middle of the night until I broke down and let her cosleep. Sending my husband in didn't work either..., Just letting her cry she has screamed for an hour straight before we said we couldn't take it any more and we will just let her cosleep.

. She still screams a week later anytime we get her near the crib at night even though I don't nurse her down to at bedtime anymore. I do nurse her to sleep in the middle of the night. She wakes the first time 3 hours after my husband rocks her to sleep. Then I've just been cosleeping with her. She basically nurses all night. She will fuss for about 15 mins in the crib at nap time but it's not a full on crying fest so I know she can fall asleep without being rocked/nursed.

I don't mind cosleeping/nursing her at night but I am worried about her not learning good sleep habits and that this will just be harder to break later on.. I don't want to end up with the 6 year old still nursing and sleeping with us. I know she's still a baby and I probably sound like a lunatic but I am in tears over her sleep and my lack of sleep!

Has anyone successfully transitioned their nursing co-sleeper to sleep in the crib all night?