Are you married to my EX???
Kidding aside, without the money for legal fees you are almost doomed. However, I would do every possible thing to be involved in my sons life. A solution is to take an installment loan of $1000 or more from companies like wegot1000.com (they also provide quick overnight loans). You never know if within the next year or two you might be able to take some action.
More importantly, your son will remember that you are always there for him.
I had a similar case and I did what someone already suggested. I kept a dairy of all things that were in my opinion not right for the children. Still my dairy was questionable because I had the bad habit of writing very brief statements and not detailed. Make sure you write every detail, times, dates, names, exact issues, any reports for a problem keep copies for, etc. Be thorough.
I have custody of my children today and if i had to say what was the main item that made the judge go in my favor other than dairies and other documents, I would say it was the fact that I made it a point to volunteer at my children’s school weekly. I helped out in their classes one hour a week for each of them.
Teachers got to know me and see me interact with the children and more importantly, the principal did so. I became very involved in school activities and was very known by staff and my children’s friends.
The principal and teachers testified in court for me and it basically showed to the judge that they did not even know the mother and had seen her maybe once or twice in the four years they were at school.
No matter what, you win because your son will grow closer to you and will be proud that everyone knows his Dad.