I'm chipping in to respond to this. I'm a SLT who specialises in autistic language development.
It sounds like you're doing a great job in trying to support your DD's communication development, but you would definitely benefit from some SLT input.
I'd suggest making a referral to NHS SLT now, as you might be waiting a long time for this to come through (2-3 years in my area ☹️). You can ask your HV/GP/nursery for support with this, or self-refer.
In the meantime, find an independent SLT who specialises in gestalt language processing and natural language acquisition. You can find a registry through these websites - meaningful speech or communication development centre.
Autistic language learners generally need different support from SLT so find a therapist who really understands that.
In terms of frequency of input, the therapist will be able to advise you on that. But the important thing is that you feel confident in using the most appropriate communication strategies for your DD at home.
Best of luck with it all.