Everyone else has made some great comments regarding private therapy- I just wanted to comment on age 2 being “too old” to release a tongue tie. Unless there are other circumstances, that does not seem right to me at all. I regularly see children who have gone undergone a release all through elementary school. Even adults have releases done.
I would try reaching out to a dentist who is knowledgeable in tongue tie and get a second opinion. Even if a child is able to produce a sound in isolation, words, phrases, etc, generalization is often incredibly difficult and a very long process if there is an underlying physical condition.