Help me to help baby self-settle?

[ChocolateHobnob]

My 17 week old DD has always been a bad sleeper. Initially swaddling helped but eventually it just frustrated her so she's been in a grobag for a few weeks now. Anyway to cut a long story short she cant sleep for more than 45 minutes at a stretch. After 45 mins she wakes up, faffs about, wriggles, bangs her legs, then cries. If I ignore her she cries louder and louder and wakes up completely. If I hold her hand (which stops her from poking herself in the eye) with one hand and pat her tummy with the other she goes back to sleep. She does go back to sleep but this is literally every 45 mins and I am suffering as a consequence - it's been like this for weeks and weeks. Does anyone have any suggestions as to how I can help her get herself back to sleep? I'm not ready to leave her to cry.

NB: She was a terrible daytime napper but I'm managing that by taking her out in her pram/the car/putting her in her swing at the times I know she needs a nap, so although she doesnt get masses of daytime sleep she gets enough not to be overtired IFYWIM.

She is exclusively bf but her last feed is at 7.30 and she doesnt seem to want another till 7 am, so the issue isnt hunger.
Thanks for your help!

have you given her a comforter - I recommend a trip to mothercare, they do machine washable ones suitable from birth (buy 2 and return the unused one if it doesn't work). Have the coforter with her when you feed her and when you put her to sleep. Eventually you may have to let her cry a bit but let her adopt the comforter as a way of self soothing to replace you?

Have you considered co-sleeping? Then you would probably find she would wake up less as she will feel you right beside her when she stirs.

IME babies get better at self-settling as they get older, DS started being able to self-settle more around 7 months, I think it takes a while for them to get used to sleeping alone.