Great insight, a huge step in the right direction. But you are not selfless by being emotional/caring towards another.
You want love/appreciation(love bombing), because this feels good for you. You feel that your worth is increasing.
You believe that by loving/helping the narcissist you will receive love back.
It's a selfish transaction, you see?
When you don't get any love back, your emotional/caring part flips to blame/anger/sadness instead. By blaming you are blind to you being part of the problem.
You need to first give the same amount of love you want to give to others to your self. Always. By doing this you are fully nurtured by yourself at all times.
This leads to you finally being in balance and able to give love selflessly. Not wanting any love/appreciation back in return. This is your highest potential. Giving unconditionally.