Cycle day 39

I'm on my 39th cycle day and still nothing, dozens on negative pregnancy tests in the trash throughout the last 2 weeks. My fiancé swears up and down I'm pregnant despite all the tests. I've been having every symptom in the pregnancy handbook. Gaining weight, eating like crazy and literally starving every hour on the hour, extremely moody, headaches, migraines, boobs are so tender, nipples are so sore that if touched I almost scream and I'm only gaining weight in my stomach. I've never felt anything like this and it so weird feeling like this. But still all the negative tests have me put off. I read online that in some women their Hcg is so low that a blood test is required to really find out if they're pregnant or not. What should I do from here?