Mistakes can be made no matter which method you choose to sex your pigeons.
If it lays an egg it is definitely female.
I find the best way to sex a bird it to ask another pigeon.
Check out the link the pigeon bowing and circling is ♂ the bird walking is ♀:
You are quite right. My top ranking old female pigeon is bigger than all my males and is aggressive, struts about, bows and coos, and bullies the males. She has a massive thick neck and is very strong. Anyone would swear she is a he, until she lays her eggs!!!!