I went to a sleep day centre when bub was 12 weeks for this issue as she only slept on me (and never more than 40min). First step was to get her to sleep in the bassinet. We used a dummy, white noise, dark room, ssshhhing and rocking the bassinet. Then slowly we stopped the rocking, then the ssshhhing and now she completely self settles in a few minutes.
Good luck! We had to be home for naps for a few weeks to get there... but now she self settles we can go out and she'll sleep in the pram