Sounds like you need a lot of space to identify who you are apart from those around you, whose personalities and self-expressions are suffocating your rightful need to gather strength for yourself!. It's perfectly okay to say to them I need some time to myself even if it does offend - it is not selfish to want your space and time to yourself whatever you decide to do with that time alone is up to you. I'm fortunate enough not to have family, yet those who do like yourself, need to allow you the time and freedom to become who ever you want and whatever you wish to be.

Try not to judge others though, they are imperfect as you already have elaborated in your post, so you know that their issues and their failings are their own carrier-bags full of their stuff - not yours. Because it is not your stuff, you should not be carrying around what they carry, you only have one pair of shoulders and not five!. Being selfish is never a negative thing, but believing that it isn't are two different things. It might be useful to you if you like drawing to sketch a picture of all the things that make you feel burdened and weighed down by others - place their bags upon their shoulders so that you can see what is your stuff and what is theirs?.

Not sure if this is helpful or not to you, but I hope that it helps on your journey - It helped me so hoping that it does help you too.