Why am i having light pink/orange discharge when i wipe? i am on the depo shot but missed one in may, unprotected sex in july but got another on august. now spotting on and off with negative pregnancy test but stomach getting big and hard

When in doubt: just check pregnancy test again. And if you are still not bleeding normally and first pregnancy test was negative, check it again in 1 week. But it is not likely that you are pregnant given significant bleeding. However the timing of the unprotected intercourse is worrisome as it occurred right when you were very vulnerable, and the Depo shot in August likely did not help prevent the pregnancy.