I had MAJOR issues with DD at about that age and nothing I did would help her settle so I created a sleep plan based on a couple of recommendations. It has been successful on the most part although I am currently feeding her once at night. Plan went as follows.
Naptime
We have a routine that lasts 5-10 mins.
Check nappy
Sing twinkle twinkle little star on the way to bedroom
Close curtains
Into sleeping bag
Read 2-3 stories
Into bed hand bunny (her cuddly toy)
Say nun-night and leave
If she grizzle cries wait 5 mins then check if still crying lay her down if sitting or standing say nun-night and leave. Wait 10m then check if still crying, then check every 15 until asleep.
If she was just grizzling I'd leave her as she often fell asleep if all was quiet I resisted the urge to check. Each check lasted less than 30secs and I was in and out, only touched her to lay her down.
My plan was I'd do this for an hour then get her up for a bit then tried again. If she still wouldn't sleep then I'd go for a drive or put her in the stroller for a walk. I never got to that point though.
It took about 4 days and she was going to bed happy for day naps.
Bedtime
Routine lasts about 30mins
Bath
massage/creams (she has ezcema)
PJs and Sleeping bag
Feed in lounge
Say good night to everyone
Into bedroom for stories (2-3)
Into bed hand bunny say nun-night and leave
At night I would do as above for checking after her bedtime routine for as long as it took to get her asleep. But again I never had to do that as she settle to sleep for the night well. I also did it for all night wakings and she now wakes once while before she was waking 2-4 times a night to feed.
Hope that makes sense and helps