For 2019 you only need to enter a 1095A not a 1095 B or 1095 C
https://ttlc.intuit.com/community/credits-and-deductions/help/do-i-need-to-enter-a-1095-b/00/26673
https://ttlc.intuit.com/community/forms/help/do-i-need-to-enter-my-1095-c/00/26674
Don't understand your other questions or problems. Did you already filed? Did it reject?
FOR AGI
You need your 2018 AGI to efile 2019. The AGI is on 2018 1040 line 7. If you filed a Joint return you use the same AGI for each spouse.
https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947
