Am I pregnant or crazy??

Annetta • Married with a 17 yo girl and 15 yo boy. Ready to start round 2!! Due 9/28! I work as an RN in SLC.
I am 12dpo. AF due in 2 days. Since about 10dpo I've had an intermittent backache and my mouth has been super dry with a metallic taste. Also on 10dpo I got a little brownish discharge when I wiped and have off and on since. This morning it was a little more the past two days. Then I start bawling because I feel like that's too much discharge for implantation bleeding. But I've NEVER experienced any of these symptoms prior to AF. Any feedback will be appreciated I'm an emotional wreck!!  oh and I got a BFN this morning :(