3 week old newborn will only sleep if bf. Help please!

[Confused40]

Hi
My 3 week old DD won't sleep unless I breast feed her to sleep. This can sometimes take hours and I'm at my wits end. Last night during a night feed she took almost 3 hours to get back to sleep.
What am I doing wrong? How can I break this habit? I'm so tired and my arms are beginning to ache even with using pillows.
Please help?

Thank you. Midwife weighed dd today and she now weighs 7lb 1oz. She's put on another 30 grams since Friday. Whoo Hoo! She also is getting better at sleeping. Although last night was a bit stressful. She is using the dummy for comfort now instead of me. Yes I hate dummies but its a life saver. I'll speak to bf support group about tongue tie, I did look at the video and don't think she has it, but I'll still get them to check it out. I'll also get them to observe a feed. I am using nipple shields and really want to stop, so have been feeding her a bit, then trying without the shield. I'll get some proper advice at the bf clinic.

I'm eating and drinking when I feel hungry and drinking when I'm thirsty. I agree with you on what the m/w saying as utter nonsense lol.

Talking of that, I'd better rush and get a spag bol cooked before dd wakes up to be fed.
I've just put her cot together with the help of ds and it looks lovely. She's in moses basket for the moment but that'll change soon. :)

Last night was another night where dd took over 3 hours to settle. Bf sleep, wake up and repeat oh and bouts of crying too! I'm exhausted! She finally slept at about 3.30 and woke at 7 again to bf.
The dummy didn't seem to help :(
Went to sleep with a headache and woken up with it :(
Roll on tomorrow and bf support group.
I am so very very tired