Help!

Me and my hubby have been trying to conceive for 3-4 months. I am 4 days late for my period and 18 dpo. I keep getting BFNs and I swear I’m driving my self crazy with tests. We wernt really trying this month, just letting it happen. I haven’t started my period but I am mildly cramping today and it’s only been today. I have been nauseous and had headaches. The other day my nausea was so bad I dry heaved a few times. Please tell me there’s still hope to be held on to that I am/could be pregnant. Cycle day 36. This app says I’m 4 days late for my period. Flo app says I’m 1 day late for my period