While healing we may confuse:
confidence with arrogance
Having faith and trusting yourself and your abilities has nothing to do with being/acting/feeling superior or presumptuos to anyone else (=being arrogant). You are just objectively stating your worth: you cannot diminish it as you cannot diminish the worth of 500 bucks. It is what it is. And so is you. Plus, no one is going to give you a prize for playing yourself down, they'll actually listen to you and not value you enough too.
having your needs met/putting yourself first with being selfish and egoist
Asking for help or support, giving love to yourself first, has nothing to do with not considering others or their needs (=being selfish or egoist). You're only considering yourself as anyone else. You need help too, sometimes a little more than another, and it's fine. It happens. The next time is gonna be the opposite. That's how life is, and how you're being balanced between giving and receiving.
assertiveness with aggression (esp. if we've always being on the passive side)
If you're setting boundaries, standing your ground or standing up for something you believe in or just yourself, you're not being aggressive. You're not attacking the other or being violent with them, you're not diminishing them (=aggression), you're just standing tall saying "no" to something you don't want to do, for example.
While healing, we are learning to be more self aware and realize where it's our past/traumatic experience speaking for us. Especially if we've been through cptsd, we have experienced multiple difficult situations and therefore we may not entirely realize what it means to have a good emotional health, and confuse some feelings for something they're not.
To find it all out, we need to get out of our comfort zone, and take a few risks. Check with the new uncomfortable feelings we get the moment we set boundaries, we ask for help, we give ourselves credit for something we've done..., and try to understand them and welcome them. But also overcome them. If we feel like we cannot control the line between the differences listed above, we can always ask for support/feedback to people around us, we can talk things out, find compromises. But remember: it's okay to just try and tell the world "Hey I exist too! I'm worthy and I have needs and likes/dislikes as everyone else". It's totally fine. It's your right.