I know this is not what you are looking for but I just wanted to chime in. I was an only child until I was almost 13, my mother had a lot of trouble getting pregnant but bH did and I have a wonderful little sister. My first point is never give up, Hashem sends miracles when you least expect them, and we all support you here and send you good wishes.
Back to my point. People used to say the most in appropriate things to me such as, ” mom and dad only wanted one kid to spoil huh?”. Or people would say, ” you are probably happy mom didnt have more kids so you get all the attention”. People alwas say things without thinking. I wanted a sibling so terribly and wished everyday that my parents would have another baby. I wish we could just zip the lips of those who say hurtful things, even though they don’t mean it. Hatzlacha!!