Thank you for the additional information.
Your mother in law does not have the legal right to limit anything. She does not have the right of a parent---despite the fact that your husband and child are living in her home. if she insists on trying to be controlling, then you simply demand that your visitation time with your 3 year old occur outside her home.
The real problem is that while you do have parental rights
---you have to have the court enforce those rights for you. While you may want to work at marriage counseling---that does NOT mean that in the meantime you should not apply to the court for both a custody/visitation order and a child support
That is the only way that you will be able to enforce your rights to see your 3 year old. As it stands now, at any time, your husband and his mother could simply not open the door to you, and you would be completely unable to see your child until you were able to get to court and get a court order---and that could take some time. As you are already beginning to have trouble now---and because the monster-in-law clearly is playing games, your only save avenue of approach is to have the court dictate the ruled of custody and visitation.
I hope that you found my answer informative, that you are accepting of my efforts and that you will rate my efforts based on the knowledge I have provided to you.
I wish you the best in 2012.