My Period Started On Jan. 12, I Reviewed The Depo

My period started on Jan. 12, I reviewed the depo shot Jan. 14. I had unprotected sex 9 days later. He ejaculated in me several times. I thought I would be protected but I'm also having symptoms of ovulation: high (hard) cervix a sharp pain in my ovary, then I had spotting for three days (brown to red then to brown again). What are the odds the depo isn't effective for me? Is it common to experience ovulation and period symptoms on depo without actually releasing a egg? Thank you so much