I suspect it is to do with relationship with mum (now passed). But even that self awareness isnt helping me be strong enough in this situation
Suspecting something might be to do with something else isn't self awareness. Work out why. What did your relationship with your Mum do that was damaging to you? What do you wish your relationship with your Mum had provided for you that it didn't?
I'm assuming that she didn't validate you, make you feel worthwhile, show an interest in your feelings? What you need to do is do for yourself what your Mum didn't do for you. So, if your Mum didn't listen to you, you need to listen to yourself. Take notice of you. You say you're a people pleaser but you don't please you, and you're a person, aren't you?
If you were 2 separate people (and you are, currently), what would the people pleaser you do for the other you?
The 'other' you is the real you. Can you separate her out and work out what she's feeling? This is a minute to minute activity. Next time you go out of your way to please someone, listen to the part of you that didn't want to do that. What does she say? She's the one you need to listen to. She's the one who says 'This guy's messing us around, tell him to go f* himself...'
Once you can separate the people pleaser voice inside you from the voice of the real you, that's self awareness. That will help you. You will be able to move forward from there.