therapy and ABA

Hello

I'm new here. Our 3 year old son was recently diagnosed. He is currently non-verbal and classified as a requester.

I'm desperate to improve his communication skills but don't know the best route to take.

We live in Essex and currently he sees a Speech and language therapist twice a month for an hour each time. With 18 months till he starts school and everyone saying that intervention at this time is crucial i feel like the clock is ticking on his chances but that we aren't doing enough to help him.

After doing some research we discovered ABA. Opinions seem very mixed on this but the one thing i have noticed is that there appears to be empirical data to back up its success and i'm not finding this with other forms of treatment, including those provided by the NHS. 

Does anyone have experience of ABA? Or success stories with other forms of treatment? Or even just general advice on how we can get more help for him at this important time?

Thank you