There are no true experts when it comes to relationships. The people who claim to be experts are people you should stay away from. Each individual relationship is different, and yours is no exception.
I was struck by one thing you said...you wouldn't even have your son if it wasn't planned to a T. Were you and your husband perhaps doing so much planning that it took the fun and sexiness out of the sex, and just made it a chore? So many couples want children so much that they will plan on having sex on such and such day at this perfect time for ovulation, and it can really drag down a relationship.
Also, it does happen that after having a child, typically the woman is so exhausted from caring for the child, focusing all of her energy and time on him or her, that she loses any focus she once had on her husband. She may also stop taking the same amount of care on her appearance that she did before she got married and had a child.
Of course, no relationship is a one-way street. Your husband must also make an effort to help with the child (it's his, too, after all), help with housework, etc, give you a break when you need one, and he should also let you know that you are still sexy to him, and not just a mom. You have to make sure that your husband doesn't feel like you are treating him like a second child. He also has to feel desired.
If you are counting the times you have had sex with him this year, stop! Do not put pressure on him to perform. It is possible too that he may have a medical condition he might be embarrassed to talk about. Don't nag, but ask him if he would go in for a complete physical.
I hope things get better for you, I do, but please don't leave your marriage until you have tried everything. Sex is good and great and wonderful, but at the end of your life, are you going to look back fondly on the sex, or will it be the relationship with an otherwise wonderful man which you will most remember to be a joy in your life?
Now, I personally don't believe in marriage counseling, since therapists are getting paid to get into your business and they have no more insight into what makes relationships work than you could already know, since you are the one in the relationship...how many marriage therapists have actually been married for 30 years or so? Lots of them are divorced, some have never been married, and most, if not all, have plenty of their own relationship problems you will never know about.
However, having said that, if you feel it would help you to talk to someone other than family or friends, you might want to consider it.
Take care, and give your child a hug and kiss. Once in awhile, give your husband a hug and kiss too, without expecting anything else...you might be surprised at the effectiveness of simply showing affection without expecting sex.