Your milieu is not the same as your sister’s. It is an ever-shifting, individual configuration of information flows. The Twitter feed you have curated is a milieu. Your friend group (which is not the same as the friend groups of the other people in that group!) is a milieu.
It is by changing your milieu that you change yourself.
Instead of asking "Are you the one," ask two questions of each of you. Do I accept my partner despite their shortcomings? Do I commit to nurture them to achieve what is important to them? And likewise, do they accept me and do they commit to me? All you need is four yeses.