Sales pipeline- Dividing money across months

I posted about this when I first started this little project and was happy to get some help. The project has progressed since then, but I've run into another question that I can't quite figure out.

The idea is to have a sales pipeline where we can enter the amount of $ from a sale and project those dollars across the months the task will span. So if I book something that starts in January, generates $500 and lasts 5 days, it should put $500 in January. If I book something in January that generates $12,000 and lasts 365 days, it should put $1,000 in each month.

Please see the attached. What I've wound up with is a long series of nested If/And statements. It seems to work fine except that December won't populate at all. I've been staring at it for too long, and could use any input. The spreadsheet in question is attached.

Thanks in advance

Pipeline test.xlsx

Thanks for your help. I see what you did, but with this solution an extra month gets added. So if I enter a project as lasting 120 days (4 months), it spreads it out over 5 months. Maybe I'm just going about this all wrong?