So mad

Okay little back story. My husband and I just started trying for baby #2. Our little girl will be 2 on September 20th. We would like to have as close to three years between kids. We’ve been trying for two months now and just said something to his family. His sister who is 14 years older than him, has 4 kids all 3 years between just told us we should hold off on trying for a little longer. Now my husband doesn’t want to actively try and BD during my fertile week unless we have the urge. Ever since his sister said something now his mind has changed. How do I approach this with his sister and him? Like we should be in agreement to try and not let others differ our opinion on when to have another child. Sorry I just needed to vent somewhere