There could be multiple issues. First, the name of the form in your post text and query design picture aren't the same. Second, you don't bind search combos to fields. Doing so will cause Access to attempt to change the data in the bound field according to the search value chosen. Reads like you have done this.
Some of your post doesn't make complete sense. Forms don't enter records all by themselves - users use forms to enter/edit records, so I don't grasp the goal when a form doesn't show a record for a month. If a user selects month and year criteria and you code to validate these unbound controls, the form will either show records or not (BTW I don't see the point in combos for this unless you're applying some sort of restriction - why not just a textbox(es), perhaps even making use of the built in calendar). If no records result, you could provide a prompt to enter a new record, in which case a Yes response causes the form to move to a new record. Not sure what you have in mind at this point, because as I said, forms don't append records without user intervention. A query could if there is a trigger event, but still, there has to be some sort of intervention.
You might want to search on the basics of making/using search forms and see if that fits with your process. I say that because a) of your apparent use of bound search criteria controls and b) maybe you need to rethink the process. Perhaps a separate search form and then open the 2nd form in accordance with the search result?
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.