You are so passionate about wanting to help your child and that is awesome! I know that I wrote to you earlier about my son and I really didn't expand on where he is academically now!
My son will be four in September. We have struggled to understand what he is saying since about your son's age. We finally got him accepted in the public schools speech program. I really don't think this is the route we really needed to take. I have always stayed home with my children and we run two businesses out of our home. I always felt like I was too busy to do fun activities with my children, but in all actuality I am sure I had a spare hour or two each day that I could have devoted to them.
I feel that my inability to actually sit down with my son and 'teach' him drastically affected his speech. I have a few suggestions for you and this comes from my recent experiences with my son, who is talking our ears off these days. Just by me starting my own preschool and childcare, he is learning by leaps and bounds!
Engage your child in a daily routine consisting of learning activities. Set aside one or two hours a day that you devote solely to your son. You can tell him that it is time for 'school' and sit down with him and engage him in different sensory activities. Here are some of our favorites:
-Play with shaving cream on the table-talk about how it feels, tell him what color it is, and have him smell it.
-Have 'circle time' where you sing songs(you can even make them up) and do finger plays. Google finger plays or children's songs and you will get a wealth of information.
-You can also choose a theme each week and do different activities pertaining to that theme. For example: Bubble Week-blow bubbles, make bubbles in a wading pool, cut out circles, trace circles, talk about the letter 'B' talk about the color blue, etc. Have everything tie into each other for the whole week straight and you will simply be amazed at what he will learn. Don't ask too many questions, this will only frustrate him and cause him to be even more timid about his speech.
-Make lacing cards or purchase some at the learning store. This is good for hand/eye coordination, but also they come in different shapes and colors and he can match the laces to the colors of the cards.
-Play memory. Purchase the actual game or make your own cards on the computer. Each time he flips over a card say the name of the object and talk about what it is. If it is a dog, say, "Dogs bark!" You can then start barking,etc. Try to flip the card over after a few more turns and repeat it again. Children learn through repetition.
-Purchase posters that have different shapes, colors, the alphabet, numbers etc. Laminate them for durability. Use a pointer and point to each object on the posters. We sing songs about the days of the week, the months of the year, etc. Make a game out of it! The youngest child in my childcare is 14 months and she even points and sings about the days of the week!
I recently purchased a Toddler Theme Calendar book from the learning store that has every week for an entire year planned out. It is specifically geared for ages 18 months to 3 years. I highly encourage you to take a trip to the store and see if you can find something like this. It will help you see that learning does not have to be all flashcards and memorization. Your son will learn by having fun with you and knowing that you have taken the time to sit down with him on a daily basis! Sorry this is so long, I hope this helps:)