This is exactly why you need a tax professional. You're linking to an article that is related to whether or not you can "write off" bad/uncollectible debt; it's not relevant. The first sentence most likely "disqualifies" you from the article's contents entirely -- you're probably not a small business that is using accrual-basis accounting, it sounds like you may not even have an entity at all (which is fine).

You need a tax professional (or even a semi-pro); in the interim, I'd suggest solely relying on what you read on the IRS website.

Generally speaking, by default you are likely cash-basis -- but yeah, this income & especially with "high variance", get with a professional. If nothing else, figure out whether you actually need a loan or not before applying/asking for one...

IANAL/IANA-tax-pro -- but you almost surely do not need a loan.