I don't think your son will fit in a bassinet comfortably, check with your airline though, but I would still request a bulkhead, if at all possible just so that your litle boy has a bit of space to play on the floor. I know that he should be strapped in, but try telling him that!
Be prepared for several laps of the cabin with him to keep him amused and don't give him all the toys you bring, just one at a time so you've something fun to distract him with. Most of all don't panic and worry because that'll wind your son up. You'll be fine I'm sure.