ECHP - 2 years behind?

[SENMinefield]

DD Y3 has HF Autism and on waiting list for ADHD assessment.

Clearly not making expected progress in school despite extra effort at home. School are doing some small group intervention work but it's clearly not enough and they are not making any adjustments for her difficulties. I would estimate she is 1.5 years behind in reading, writing and maths, although she made amazing progress in reading during lockdown due to the 1-1 at home.

We have mentioned to the school on several occasions that we would like to apply for an EHCP but the SENCO actually laughed at us and said DD needed to be at least 2 years behind her peers.

I think we have nothing to lose by applying for one. Or is it true that a child needs to be 2 years behind to be considered?

There is no 'official measure', although that is something that is often bandied about. The child's SEND needs to have a 'significant impact' on their learning.
Of course, there will be a whole range of ability within all the dc in the country in Year 3. What measure(s) are you using to guestimate she is 1.5 years behind ?