How can I build a 6–12 month cash flow forecast for inventory and tax payments?

[Mark_M]

I run a small e-commerce business selling handmade goods, and while we're profitable on paper, I constantly feel blindsided by cash crunches, especially around inventory purchases and tax payments. My current forecasting is just a basic spreadsheet looking a month ahead, but it's not helping me plan for seasonal dips or growth investments. For other small business owners, what methods or simple tools have you found most effective for creating a reliable 6 to 12-month cash flow forecast that accounts for variable expenses and helps you make smarter spending decisions?