You've had a lot of great "don't worry about it" responses. But it also sounds like reading with your son is something that's important to you that you want to continue.
My daughter didn't show much interest until after her first birthday. She decided when it was time for long stories. I agree that reading works best when baby is in a quiet, snuggly mood. If he's playful, make reading as silly and physical as possible. Remember that the message you're conveying right now is READING IS FUN.
Get some books that are cloth or plastic (tub-friendly) for your son to play with. He can chew on them and throw them without damaging anything. Just let them be toys, and put them where he can reach them. Occasionally point out the pictures.
Here are some suggestions for types of books to look for as he develops an interest. Some may help now if you want to keep trying, and some may be more appropriate later:
Books with baby faces! The text doesn't matter. You can just point to the baby and say what it's doing. Our library has a series of baby sign books that have great pictures of babies doing things, even if you don't care about signing.
Make a photo album with pictures of family members he knows, and label each picture with a name. As you turn pages..."Look! There's Daddy!" "Where's Grandma?" I actually uploaded photos to shutterfly.com and took advantage of one of their free photo book offers to have it printed and bound just like a real book.
Board books with photographs of animals...Instead of reading the text, make the animal's sound.
Hand puppet board books: http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3... ...Wiggle each puppet as you go. Let him grab and manipulate them as you go.
Rhyming books, and books with sound words. Sandra Boynton board books are great. There are also lots of books that use song lyrics or nursery rhymes as text.
Board books with textures on the pages.
Counting or ABC books with bright pictures. Try Karen Katz.
If something particular interests him (say, balls or cars), try to find books with lots of pictures of those objects.
And...Maybe instead of reading, try sitting him on your lap and doing nursery rhymes or songs. It was something my daughter loved at his age. "This Little Piggy," "The Noble Duke of York," "Head, Shoulders, Knees and Toes"...All will provide interaction with you and convey the rhythm and flow of language. Check out the free children's programs at your local library. Ours have infant story time, and the librarian teaches LOTS of these little rhymes that have physical actions to go with them.
Enjoy it!