Late period

I've been on depo for roughly 5 or 6 months my last proper period was the 22nd July and lasted 6 days. On the 10th august for a few days it was light brown spotting we had been using condoms but we did have unprotected sex on the 2nd September. My period still hasn't shown and it says 9 days late.

Should I take a pregnancy test next week or is it too early?