To do DCF you need to do a few things either before filing or while waiting for the Embassy to process your case.
- You need to reestablish domicile in the USA, use your parents home, if you receive mail there get the mail to show that address as domicile, also state drivers licesence can be used, as well as US bank accounts.
- File any IRS returns that you may have not done, you may be exempt from paying US taxes on foreign income, but are not exempt from filing an anual return with the IRS. You can file late.
US domicile and IRS returns are needed for the affidavit of support, and the I-864 affidavit of support is needed for the visa.
You can use someone in the USA as a joint sponsor for the I-864.