Pregnancy or af stress 🙁

I’m currently on 12 dpo I have no symptoms of af or pregnancy except sore boobs and I guess I’m more sensitive to temperature. Anyways I have tested on 11 dpo bfn . Currently taking l arginine . When shall I stop taking it ? I was told in order to get a period some hormones drops . So , I’m really concerned I won’t get time to try again as my husband is travelling .