Something is definitely OFF about this, the UPGRADE doesn't create an NEW tables, so you getting an error message about NEW TABLES not existing is baffling to say the least.
Now, I could understand if you attempted an upgrade and the upgrade FAILED and then you tried to upgrade again and got an error message "table x does not exist", because the first step of the XF2.0 portion of the upgrade is RENAMING the AMS 1.x tables, so the system won't be able to find them since they've been renamed already.
If a partial upgrade happened, Im going to need to figure out why it failed and finish it for you. Can you please start a conversation with me and provide me credentials? I'll need Admin CP access (full admin) as well as DB access (phpMyAdmin).