The number of adults seeking autism and ADHD diagnoses has increased since the pandemic.
Some people in Wales have been waiting for more than two years for a diagnosis as the NHS struggles to keep up with an increase in demand.
Around one in seven people in the UK are neurodivergent, but barriers to diagnosis and treatment including gender, waiting times and a lack of understanding.
Charities continue to warn that many people, espeically girls and young women, are 'slipping through the net', despite neurodiversity becoming better understood.
Missed diagnosis and increased understanding has combined to result in an increase in adults seeking diagnoses, and in turn pressure on services and waiting lists.
History and politics student Charlotte is currently waiting for an autism assessment, after referring herself to the West Wales Integrated autism service.
She fears she won't receive the support she needs before she graduates.
Charlotte, 19, told ITV's Wales This Week: "If the wait is as long as they say it is I won’t have had any support throughout education. Not one drop.
"Girls like me that slip through the net in school have now got to battle with the grown up system on our own. I would like to say it gets better but I can’t honestly say that.
"If you slip through the net the adult system is cruel. It leaves a lot of girls and women behind without the support they need, not only in school but in their workplaces."
Hywel Dda, the health board responsible for providing health services where Charlotte lives, confirmed the current wait for an adult autism assessment is one and a half years.
ITV Wales asked Welsh health boards how long their current waiting list is for assessments for autism and ADHD.
Of the five that responded, the longest was more than four years.
What is neurodiversity?
It is a term used to explain the range of differences in individual brain function and behavioural traits.
People who are neurodivergent process things like information and emotions differently
Neurodivergent conditions include:
Attention deficit hyperactivity disorder (ADHD)
Charlotte explained that she had always felt "different" during primary school, but other children struggled to articulate to her why they couldn’t play with her.
"I have these sensory issues surrounding certain foods, certain textures, lights and noise," Charlotte continued.
"For me it’s been a lot of little things that on their own could mean anything, but all together might mean autism."
Charlotte's brother was diagnosed with ADHD as a child, but she believes she was missed in school because she was able to mask her symptoms.
"I think because I was always ahead of the curve at school, I was always years above my reading age, years above my numeracy age, it was just like - she’s bright, we’ll leave her, she’s evidently doing well in school.
"But obviously not on the social side. It wasn’t a secret that I was different, shall we say.
"I’d make a friend for a few weeks and then they’d go, she’s different we’ll get rid of her. And then eventually I just learned to be quite happy on my own, I still am. I just sort of get on with it."
Research has highlighted that women are often diagnosed with conditions like ADHD and autism later in life.
One of the explanations for why many females continue to go undiagnosed is that symptoms have traditionally been considered from a male's perspective.
Professor Amanda Kirby, who has dedicated her career to improving support for people who are neurodivergent, said: "Over the last few years we’ve recognised that women have been missed, misunderstood and misdiagnosed.
"Clinically, I would be looking at a tick list of ADHD traits, but what I was having was a male list in front of me. And not recognising that girls with ADHD present quite differently.
"They’re less overtly hyperactive. They might be active but helpful, so not disruptive. There’s many women who have been treated for anxiety, depression, eating disorders, and not realising that some of that might be due to the ADHD traits.
"Understanding that now really making a big difference to their lives, and the same goes for autism.
“Females often mask, or conform or fit in - even at a subconscious level - but it’s exhausting and often people have mental health challenges as a secondary consequence of that.”
“I’m optimistic that we’re starting to talk the right language and we’re starting to put some guidance in place which means people have somewhere to go to know what to do."
Despite the number of people on waiting lists for a diagnosis in Wales, Professor Kirby reinforced that receiving a diagnosis can be "key" for people to access the additional support they need.
"At the moment it seems too many people a diagnosis makes a big difference" she continued.
"It’s often that golden ticket, which is why people drive towards it, to get an educational healthcare plan, to get disability student allowance, disability living allowance, access to work.
"People need that diagnosis, that ticket, to get that additional help. And that’s a medical model for something that is often a social challenge."
The Welsh Government has committed an additional £12m over three years to improve neurodivergence services while strengthening support for families and carers who are waiting for an assessment.
Earlier this month it set up a 24 hour helpline to make support more accessible and inclusive, and signpost people to the help that’s available.
Julie Morgan, the Welsh Government's deputy minister for social services, told ITV Cymru Wales: "I think it’s really important that some of the social aspects, for children in particular, are addressed.
"We’ve been able to grant voluntary organisations to provide youth clubs, to provide drop in centres, to provide some training and education.
"With early help it is possible that some of them don’t need to be assessed and don’t need a diagnosis, and hopefully by getting in early they will get help in other sorts of ways.
"So, we’re trying to approach it in a much more holistic way."