I recently ditched the dummy for my 5 month old - Elodie. She sleeps much much better but still occasionally wakes after 40-45 mins from her lunchtime nap.
Not sure how to help her make the transition. I let her cry for 10 mins to see if she will resettle. Generally, it just escalates unless i go in and feed her, let her suckle herself to sleep again. Or take her into bed with me for another hour and a half.
When we are out and about, she will sleep happily in her pram in the fresh air and sometimes even needs to be woken up. But in her room, she only sleeps 40mins at a time.
Wait until she is a year old!! DD1 NEVER managed to nap for longer than 40mins in her bed until she was a year old, when miraculously she broke the barrier. Until then she would sleep 40mins in bed and 45mins on the boob for both naps.
mine was/is 9 months, all my maternity leave he only ever slept 40 minutes in the day at a time, then back to work on tuesday and he has decided to start sleeping 2-3 hours after lunch, also obviously coincided with him starting going to nursery trial days. I tried everything, couldnt do leaving him cry or hope he would go back to sleep it didn't work, like you the only way i could get him to sleep loonger was to go to bed with him my self. I finally accepted it and went up to him when he woke up and go him up, this was after months of trying to nurse him back to sleep.