Is my child delayed ?

Your child may have a different way of learning than school does. There are visible learners, kinetic learners, verbal learners, an audio learners. Schools don't always cater to children with different need.Because of the different ways they learn. So school standards don't always work for every child.
I think you're doing an amazing job.

I agree with Amelia you are doing great unfortunately schools have a strict tick box for learning milestones
Keep encouraging learning in a fun supportive way
You know your child best

I mean... I don't have a 4yo but this sounds like normal shit to me. Kids take years to be able to correctly identify colours, shapes, numbers. And many times they can identify them correctly at home or in a familiar setting (like you said with the number line), but cannot do the same in a novel context. I think it will click. I don't think these are things she necessarily NEEDS by 4 years old - she can learn her colours and numbers etc. pretty quickly in school, that's what it's for.

I think preschool puts too much emphasis on academics tbh, and I've heard grade school teachers complain about this problem. They get kids in their class all the time who can recite their letters and add simple numbers, but don't have the finger strength to write their name because instead of playing with playdough, they were learning academics. Kids learn best through play, that's what she should be doing right now.