Hi Dacia,
I'm a speech and language therapist working at the same place as Vanessa Elliott.
Speech and language delays can be very stressful for parents and families and there are so many different reasons that children have problems with language acquisition. I think that you have made the correct decision to seek help and advice at this stage.
I would advise that you arrange an initial assessment. With our company, this is usually an hour. This time will normally be spent taking a case history and some informal, play-based assessment of your child. Your therapist should then be able to talk to you about the things that you can do to help support language. If you are finding that your son does not always understand you, then my guess would be that the focus would be on developing his comprehension first. This means working on developing his ability to follow instructions and understand basic concepts. A child needs to understand words before he can use them. Also, I note that your son is trying to combine words but that this affects his intelligibility. I would suggest that you focus on the combining by repeating back these phrases to him and don't worry to much about intelligibility; that will come later.
Often there are very simple strategies that you can use to help language development. Your therapist will give you ideas to try at home. It may be appropriate to have some direct therapy and you should find out how many sessions, the price and the targets for the course. Children can also be seen in groups, which is a great idea for little ones, so ask if this is an option. With our company, the cost of the therapy is then shared between parents and this can be a more cost effective way of getting input.
I'm sorry that I cannot give you any 'real' advice, but language difficulties are individual to the child and intervention needs to be tailored as such. Please feel free to PM me your email address and I will forward you the fee schedule and details of our company.
Good Luck!
Karen