There are a number of different things that may cause you to miss your period. For example being pregnant, low body weight, increased exercise, stress, hormonal imbalances etc…
As you have done two home pregnancy tests it is safe to say being pregnant is not the cause of your missed periods. I would recommend going to see a health professional and discussing your situation with them to see what could be causing the change for you. Let us know if you need help finding someone in your area.
Missing your period is not a symptom of having a STI. The most common symptom of an STI is feeling fine. If you are concerned an STI could have been passed to you just talk with the health professional you see and they could order some testing for you.
Have a look at the options for sexual health website for birth control information. They list the different options that are available and have a number of clinics around BC.
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