I'm not clear on exactly what you'd like, do you want one view that combines actuals with the projection across months, or just one projection? I've attached a workbook that uses a count of Order ID using the Superstore Sales data to show a worksheet with a Monthly Total of Orders to Date and a Moving 30 Day Total of Orders. Both of the fields are table calculations, and there's a third table calculation called "Filter for Today" that is used to hide all results but the the current date. The Compute Using for the Monthly Total of Orders must be set to the Day of Order Date calculated field, the others can be left at the default Table (Down).
Hope this helps!