Hi K.,
It sounds like your son may be transitioning into his new center and experiencing some emotions around it. Just as you are having anxiety about being away from him, he is adjusting to not being with you.
A lot of moms have to go back to work and their children do adjust. I do believe children are better off with their moms at home, but sometimes we can't create a stay-at-home situation.
Give yourself and your son some adjustment time. Be there for him when he has his tantrums by holding him and reassuring him. He needs to feel secure and safe.
If you actually had the ability to put your career on hold until he was about 3, I would encourage you to explore that option. If you must work for financial reasons, then be gentle with yourself - you love your son and he will know that from your consistent response to him when you're together.
Best of luck!! Please visit my website www.noblemother.com