If you are a US citizen, then you are required to file a US tax return and pay US income tax on all your worldwide income. It doesn’t matter when you entered Germany or how long you have lived there (in some cases, if your only income is from the foreign country and you lived there long enough, you can exclude that from US income tax, but that does not apply to you since your income is from the US).
If you are married, you are required to file as married filing separately or married filing jointly with your spouse. If you file separately, you are not eligible for earned income credit, that is disallowed for the filing status “married filing separately.“
If you file a joint return, you must first make an election to treat your spouse, who is a non-resident alien, as a US resident for tax purposes. Then, you must report all of your spouse’s worldwide income along with your own and pay US tax on it. You can take a deduction or credit for foreign income tax paid. However, one of the ways that you can exclude your spouse‘s foreign income from US tax will also disqualify you from earned income credit.
You don’t file a split US tax return. You will never file a form 1040-NR for a nonresident tax return unless you renounce your citizenship. As long as you are a US citizen, you are required to file a US resident tax return, even if you are not living in the US. (As mentioned, if you live overseas long enough, and your only income is from non-US sources, you can exclude that from US taxation, but you still have to file a return.)
The date you moved is the date you moved, the US does not take into account your visa issues with your new country.
