Should my just barely 9 month old son be weighing 22 pounds? is that a little overweight?

Depends: That's about the 75th percentile for 9 months. If his height is in the 75th percentile, then no, he's not over weight. What's more important is how he is growing and developing. To ask if a 9 month old is over weight sounds like he's being compared to other babies instead of just seeing how he is doing without comparisons. If he's doing well, don't worry about it; just enjoy him.