"My last couple of years" — singular or plural?

Solution 1:

Formal agreement requires weren’t. That’s because the subject of the sentence is the plural years, premodified by my last couple of. However, in terms of notional agreement, My last couple of years can be seen as an integrated whole that calls for a singular verb. Which you choose depends partly on your own view of the relative merits of formal and notional agreement, but also on the likely reaction of your intended audience to your choice.

Solution 2:

In most noun phrases with of it is the grammatical number of the head noun, not the noun in the prepositional phrase following it, that determines the grammatical number of the verb. So, we write:

• The bottle of pills is missing.
• The bottles of water are now cheaper.

But couple, in the noun phrase a couple of, is what the Cambridge Grammar of the English Language (p349) calls a number-transparent quantificational noun, meaning that it allows the number of the oblique to percolate up to determine the number of the whole NP. [Oblique is the term the CGEL uses for the noun in the prepositional phrase beginning with of, and NP stands for noun phrase.]

As well as a couple of, the CGEL lists a lot of, the rest of, plenty and others as number-transparent quantificational nouns. The upward percolation is exemplified with the phrase a lot of:

• A lot of money was spent on travel.
• A lot of protesters were arrested.

On this basis it might seem clear that the OP's sentence should read:

• My last couple of years as an Edison Eagle weren't all about fighting and bad friendships

since years percolates up to determine the plural of the verb. But, it is in fact not so clear, because plural nouns are often conceptualized as singular entities. That's why we say, for example:

• Ten years is a long time.
• $20,000 dollars is a lot of money.

The CGEL uses the term override for this common mismatch in grammatical number between subject and verb. So, if the writer is strongly conceptualizing the two years as a singular measure of time, then :

• My last couple of years as an Edison Eagle wasn't all about fighting and bad friendships

would seem to be acceptable - although I suspect that rather more people would consider wasn't to be a mistake than weren't.