How do you actually manage money with irregular income?

Genuine question for freelancers and digital nomads.

I've been freelancing for a while and the hardest part isn't finding work - it's knowing what money is actually mine.

Some months I make good money. Other months are slow. But I never know:

• What's safe to spend
• What I owe in taxes
• Whether I'm actually ahead or behind

I've tried spreadsheets. They track numbers but don't reduce the stress. End of year still feels like a surprise.

Curious how others handle this:

• Do you have a system that works?
• Any tools you use?
• Or do you just wing it and hope for the best?

Not selling anything. Just trying to figure out if I'm the only one who finds this stressful or if it's a common thing.