Trying to find my younger half-sister

So I always had suspicions that my mom had another baby after me that she gave up for adoption, and now that I know for a fact (my uncle, her brother telling me so) after my mom is deceased. she’s about 13-14 years old now and I want to try and find her. I only know the approximate year(s) she was born and what hospital. no name, birthday or anything else like that. she was adopted only a few days after being born and the adopted parents named her. I have done ancestry, 23 and me and GEDmatch all years ago, but i fear she hasn’t done those at all. could someone point me in right direction of what I need to do next? my guess would be emailing the hospital that adopted her out. I tried adopted.com but they want $20 for a membership and I am flat broke dealing with medical issues. thank you in advance.