K.L.
Speaking from experience from going through the AG's office and hiring an Att, I can tell you that the AG's office will take forever to move on it and you won't get near as much. The AG's office works for both the custodial and non custodial parent.
If you hire a lawyer he/she will only be working for you.
My ex was making about 120k per year and the AG increased my child support from $250.00 a month to 500.00 per month. Due to the fact that he was behind about $12,000 in back child support, I hired an Att. She told me that he was supposed to be paying me $1200.00 per month, plus back pay. I am not greedy, so I asked the ATT to only increase it to $800.00 per month. I started receiving the increase the next month. Yes, she cost me about 800.00, but it was well worth it. It paid for it self in about 2.5 months.