Can I sue for unpaid support after child is 18?

My ex has been in the military over 20 yrs and is currently stationed in Germany. For years I tried to get her to send consistent child support without going to court. She would tell me lies about her sending it from she sent it to Western Union or in the mail, but it never comes. She even put it and money for our son's Bday then took it back out before I could get it. My patience finally ran out so I went to the state for help.

The state of NC contacted her and after getting her 1st Sgt involved they were finally able to her income information. They then tried to send her the order to pay by registered mail, but she sent it back unclaimed (but said she never received it). The state said that since she is in Germany and won't accept the order they can only ask her to sign a voluntary agreement. They again had to contact her 1st Sgt before she agreed to voluntarily send support.

Unfortunately, she denied getting the 1st couple, claimed a lawyer was looking over it for about a month, and claimed she sent it. Long story short, the state never received the sign voluntary agreement. Her 1st Sgt said he can't do anything if it's not court ordered, but thought she had taken care of it already (she told him this). I have countless email communications about this child support situation that shows her many excuses and lies.

My son turns 18 in a week. Can I sue for the unpaid support based on the calculation done by the state or is there ANYTHING I can do?

[AFFA]

I wish to inform you that for having child support you require a court order. From the date court provides about payment of child support a person is liable. In this regard you will first require to have child support order from court. After court has passed order then you can provide a copy of order to Defense Finance and Accounting Service which will garnish the salary for child support amount. If the child is about to turn 18 years and at present there is no child support order then you will have to show to court that you are entitled to child support retrospectively.

AFF