How can I?

So I'm 99% sure I'm out this month. We've been trying for his #2, my #3 for 7 months. We're exhausted. Emotionally and physically. But at the same time, we don't want to quit because we don't want our youngest to be SOO much older than her baby sibling. How do I "not try" this month? All I can do is count days and analyze everything about my body. How do I turn that off? We'd like to take a month off, but I don't know if I can. Any advise?