Generally, once support is ordered, the order will apply back to the filing date. You have a problem though, you said the case has been closed a few times. You need the help of an attorney.
Or, at least, go back to the state and find out why the case keeps getting closed. The state may be a lot of help if OP simply asks some questions. It could be that OP failed to sign the appropriate forms and once she does so, everything will go smoothly. If that's the case, there wouldn't be any need for an attorney.
So, OP, I would suggest that you first talk with someone at the state about your case to find out what is going on and what it takes to fix it. If you understand what they tell you and are able to follow through on what they say needs to be done, then you may be OK without an attorney.
If, OTOH, you don't understand what they're telling you and/or the actions they tell you to take seem more complicated than you can handle, THEN you should get an attorney.