Hi,
I'd like to echo the advice you just got, just to let you know that more than one person has the same experience. I understand your concern, but I believe the worst of your fears have passed.
Even though I've got four kids, I still worried every single night; long past the time I should have been worrying. Each time, a nurse or doctor would assure me that once my baby was strong enough to lift his head, hold his chest off the mattress and roll over, he was out of the highest risk. If you're still uncertain, you can always buy triangle props or (not likely at 14 months) attempt to swaddle him into position ... but truthfully, he's telling you that he's old enough, strong enough and determined enough to pick his own sleeping position. Just make sure that his crib is clear of big soft toys that might smoosh up against his face as he shifts around. If you're like I was, you'll be checking him so often that you can remove the mush-able things from his crib almost as soon as he starts dozing off -- giving him the temporary comfort of soft 'friends' and you the nightlong peace of mind that comes with knowing his breathing area is clear.
Best of luck! :-)