Last year I had a $1600 child tax credit and this year only $350...nothing changed for me...did something change in the law?

Nothing changed in the law.

 Did one of your kids turn 17?  This comes as a big surprise to many parents the year their child turns 17. A child over age 16 no longer qualifies for the Child Tax credit (CTC). Although a child can still be a student dependent through age 23, and a qualifying child for EIC,  the Child Tax Credit expires the year they turn 17 and you no longer get the $1000 CTC.

Your income is too high. The Child Tax Credit (CTC) is phased out at higher incomes starting at $110,000 for joint filers  ($75K single). You lose $50 for each $1000 (rounding up) your income is over that threshold.