Hi K.. My son is 18-months and isn't talking much yet either. I had been reading, singing, and doing nursery rhymes with finger play with our son, taking him to play dates and story times, etc. What I didn't think to do much yet is to ask him questions and wait expectantly for his response. I also should have been offering him choices and when he gestures towards what he wants (juice or milk, car or ball), I should say, "Oh, you want some milk", etc. Our pediatrician referred us to Child and Family for a speech evaluation, which we took him to this past Monday. He grew fussy (tired and hungry), so we're going to continue the evaluation and follow up next Monday. She watched him play, asked him questions to see if he could follow any directions (he understands way more words than he can say), and tried to get him to talk (but he just said his favorite word, "Cat"). She did recommend that he get some speech therapy. It's bad timing for us, because we're getting ready to move away and we'll be without insurance for a couple months while my husband switches to a new job. Hopefully it won't be too expensive to pay out of pocket for his sessions.
I would just suggest that you go ahead and get your son an early evaluation so you can get him started with early intervention and get all their information. We got 30-40 pages of material all about speech milestones and what we should be doing to help him develop. I've heard that some places around Charlotte, like the Watkins Center, offer free evaluations and use a sliding scale for therapy, so that would help with the cost, but that's only until the child turns 3. The earlier we start getting help for our children, the better off they'll be and the easier it'll be for them to catch up if they need therapy. :-) I know it's a little scary, but the more informed we are, the better we'll feel about it. Good luck.