Delayed development

Ta

My son will be 11 months on August 2nd and he’s still not pulling up to stand or standing with assistance. I called the pediatrician’s office and the nurse said it sounds like he’s delayed, but there was really nothing they could do until his 12 month appointment when the doctor assesses him. I feel terrible like I’ve failed him somehow 😞 If he’s still not where he needs to be at 12 months, what can I expect?