Speech delay after grommet/ventilation tube insertion

Hi there. It was obvious that my daughter had hearing difficulties from a very young age (speech never really developed "normally" at any age) and a hearing test showed that she did have fairly moderate hearing loss, and we were told she needed tubes inserted. Due to a very long waiting list and our financial situation, she didn't get the necessary surgery until just after her fourth birthday. Since the surgery she is much more social and her speech has come along leaps and bounds. That being said, there are still certain letter combinations that she has trouble with. She can say the letter "s" in the middle and at the ends of words, but has trouble with saying them at the beginning of most words. She can usually say them when coached, unless they precede the letters "m" (as in SMurfs, she always says "SLups") or "w" (as in SWim, she always says "SLim") and the "f" at the end of words (again, Smurf comes out "Slup"), but she can say it at the beginnings. Again, there is a 2 year waiting list for state funded speech therapy and we can not afford to go private right now. What can I do to help her along with this, or is it something that will eventually sort itself out?
Any ideas or insights will be greatly appreciated, thanks in advance.