He sounds a lot like my son. He is now almost 3, but I had him evaluated at 18 months :-) Hey, I figure, why wait? Nip it in the bud!
Anyway, my ped referred us to a speech pathologist. She did an evaluation at 18 months. He tested 6 months behind, I believe, but at that age there isn't a whole lot she can do. She gave me lots of ideas and said to come back at 24 months. We did, and I think he still tested about 6 months behind. Still not far enough behind to be too worried, and again, not much she can do at that age. Back again 6 months later, and that's when she started seeing him every other week for about 45 minutes.
He's doing really well, and they have a really good relationship. He is still definitely behind where he should be at almost 3, but he is definitely making progress and I'm not sure he would be doing this well if we weren't receiving services.
Now that he's almost 3, we have begun the process in the school district, so he will begin receiving services there.
Call your insurance company and find out what they will cover - a certain number of visits, any number until age 3, certain clinics, do they require a referral from your ped, etc. Many will cover until age 3 when the school district should take over. We are very fortunate because ours will cover 60 hours in his life-time, and we have only used about 20.
If your insurance doesn't cover it, or only covers a small portion, call Early Intervention. If you can't find them or just don't know where to begin (I don't), just call your ped's office or your local school. They WILL know who to call to help you out.
He sounds like he is below age level and that's something you want to address as soon as possible, but that doesn't necessarily mean there's anything else wrong with him. Lots of kids have speech delays. It's really important to address it because, you're right, he probably really does get frustrated and can't communicate his feelings. Also, you want him to have the best chance for success in school, and that really begins now. The more he can learn and the better he can communicate now, the better off he will be in kindergarten.
Best of luck!!!