How do you know that your male cat has been fixed correctly?

I ask this because we have recently noticed my cat artemis which is a male, that we are thinking he may not have been fixed all the way. Before I found him I can only assume he was a stray that was fixed through the feral cat program cause his ear is tipped. But we've noticed that he has started peeing alot around the house and he is always trying to go after our two female cats. Plus we have noticed it does look like his testicles are getting bigger. Could it be possible that he was not fixed all the way? I thought the testicles are supposed to be removed at the time. I just want to make sure cause both of the females were strays that had been done the same when we got them. Depending on the possible answers, I may end up taking him to the humane socitey to get checked out to be sure. thank you if you're able to answer with good advice.