Firstly, are you sure it's your spleen and not your stomach, liver or pancreas?
I don't have time right now to find a good, anatomically correct diagram...but go to Google, type: spleen, pancreas, liver , then enter, then on the left click on Images...and start checking it out.
It's REAL easy to mess up on that side of the body...everything is squished together (like everything else in the body), but there's a lot more 'potential for error' on the left side than the right side.