I'm 3 weeks late but negative tests

[Anon918]

I have had regular periods for four years straight . In May I was put on birth control and I've still been regular. I ended my last period on July 21st had a lot of sex the next day and then got a uti three days later which would be the 24th and had sex that day too. On the 29th I started bleeding brown blood and figured it was associated with the uti.Around August third everything cleared up with antibiotics but now I'm 21 days late and on the 8th day late I was having some brown discharge ( maybe 3 drops a day) for three days . I've taken home pregnancy tests each week of my missed period but they came out negative
Nothing has changed in my routine ( no extra stress or exercise or change in diet) my breasts and nipples are sore ,frequent urination( really unlike me) increased appetite, nausea every day ( also not like me) and I started getting a white/ clear discharge this past week and a half( also not normal for me)
I can't get a blood test because my mom doesn't know I'm having sex. But all the home tests are negative ( tried different brands)
Could it be that my levels are too low to detect or maybe it's right and I'm not?
What should I do?

[specialmom]

Being ill or having an infection can make your period late.  It's common.  So can stress, losing or gaining weight, changes in routine.  So, it could just be that.  Hormonal imbalance even if temporary for a month can cause it too.  I see you say you have no real reason for being late but this is also not common as it can happen out of nowhere.  If you are having unprotected sex, pregnancy is always a possibility.  So, you are smart to test.  They are accurate but you are right again, you can get a false negative if you test at the wrong time.  And if you are irregular for a cycle, it's hard to know when the right time to test is.  I'd wait one full week, not worry about this and retest if it is has not started yet.  After that, you can see your doctor.  Most docs want you to have a period at least ever three months.  It's frustrating, I know. My guess is you are not pregnant but having a really off cycle. good luck