How to be confident?
Let go of other people's expectations
A lot of insecurity stems from holding yourself to a standard that someone else made up. Just like the above point, no one has walked in your shoes and you have not walked in theirs.
What other people expect of you is irrelevant. It should never be how you define your worth. You know what you're going through, you know what you've been through, so only you truly can know what it is you are capable of.
Free yourself from other people's expectations. Yoube the decider of your worth. You be the decider of the expectations.
When youcan reclaim this power, you'll realise that a lot of this unease in yourself has been because you've been trying to prove yourself to someone who can never truly understand you.