So you CAN take Spanish 1 or 2, buy you won’t get additional credit for them. I would take the option of taking Spanish 2 over, even without additional credit, or taking Spanish 3 and being so far behind you have little hope of doing well. The point of attending school is to learn, not to accumulate credits. Credits allow you to graduate, but I doubt your school doesn’t leave any room for failure. I doubt you need to earn the maximum number of available credits every year in order to graduate. If you really need to credits, then drop to level 1 in another language.
Why did you “self teach” Spanish 1? That is the problem right there - you skipped Spanish 1 and went into Spanish 2 with no foundation. If this were a transfer between colleges, and Spanish 2 at the other school didn’t even qualify as meeting the standards for Spanish 1, you would get NO transfer credit.