My soon to be ex-husband will not give me son back or let me see him.

The general rule is that if you already have an attorney handling this matter, you should be consulting with him or her, rather than looking for advice on this forum.  It would be a bad idea for any attorney to second guess your attorney's advice, without knowing a considerable more about the specific facts in this case.  In any event, when you discuss this matter with your attorney, you should discuss whether he/she can file any motions on your behalf, such a contempt motion against your ex-husband for violating the co-parenting agreement, in order to get the court to step in and enforce your visitation/custody rights.  Good luck.