16p11.2 microdeletion in a child under 6. What proof will i need to claim DLA?

Hello. Im gonna say how i think it is and then hopefully someone will tell me how it really is. My daughter has a genetic disorder. The deletion itself could in future manifest in many different ways. 25 % chance of being on the spectrum, delayed speech, obsesity, seizures , schitzophrenia you name it it may all still show up or not. She was born with a 9m hole in her little heart and some very weird artery structures that somehow countered the hole and kept her alive. the veins were wrapped arounfd her left lung restricting 90%. The surgery was totally sucessful. But now Shes  behind with speech very agressive with other kids , doesnt share, almost always shouts  worrying tendancy to hit herself and giggle... stuff like that. My real question is..Does anyone feel Id need actual psyche reports and neurodevelopmental i dunno observations and stuff? Or will it be enough to show the diagnosis and support my claim with expert analysis of what this could very well mean for her? If i understand the Equalities act right, then children under six are treated differently? Anyone who can help will be so welcome. if your child has 16p11.2 and youve been through the claims process, id really appreciate ur help. Thank you.