Hollowheart,
I am still finding my way dealing with the loneliness and the ambushes every day but it pains me to see you in such an agony. There are something I am doing that may be helpful to you.
Have you heard of Faster EFT (emotionally focused transformation)? it is quite a simply technique, you tap around your median points - right or left side of the forehead, temple, , underneath your eye, and your collar bone, saying " let it go" , then hold your wrist saying " peace". It is in line with the tai chi principles. You can repeat the technique as frequently as needed. It would not take away the grief but it does give you a break in dealing with the crippling sadness. I find it most useful at bed time.
Another coping mechanism is to write down what you want to say or share with your sister - they can be very tedious. At the grief counseling session, share them with your counselor as she were your sister.
Losing a sister is very different than losing a spouse. We never had to look for love or soulmate, our sisters were here to share our lives,for better or worse, with us since they came to this world. Like you, my sister and I were never apart and did everything together, I never had to tell her how much I loved her or treasured her, it was mutually understood without uttering a single word of love.
There is another good way to meet with like-minded people - see if there are "meetup" groups in Chicago and put in your interests.
I know I will never get over the pain of losing my beautiful younger a sister. I have decided to dedicate my life to carry on my sister's legacy by being charitable and doing volunteer work, it gives me a purpose to live and to be a contributing member of the society. I still have suicidal thoughts and the continued wailing does not go away anytime soon, It is to be expected with loss of this magnitude. In your case, you can start looking for a career change when you are mentally and physically up to the task as a way to honor your sister.
Wishing you better days ahead.