You will have to wait.  Once you e-file a return, you cannot get it back or make any changes to it.  You will have to wait until your return gets accepted or rejected to make any changes.  Do not make any changes to your e-filed return, it will not go through.  The IRS is not accepting returns until Feb. 12th, you will have to wait until then to see if your return is accepted or rejected.

If your return gets accepted, the IRS may send you a letter asking for the missing 1095-A form.  The amended Federal return (1040X) will not be available until around Feb. 28th (subject to change).

If rejected, you can enter or change your information, then re-e-file.

If accepted, you would have to amend your return to make changes or add information.