Speaking from firsthand experience, I nearly succeeded at an attempt just weeks from my 18th birthday using an entire bottle of Rexall sleep aid (100 tablets), but my death would have been a very long, painful death had I gotten no help. The likelihood of you being figured out before you're found dead is very high, I'd imagine.
I remembered the day I did it, I waited for my stepfather to go out of town on vacation, and I took the entire bottle at home, drove to the high school after vomiting and losing feeling in my legs to such a point I couldn't stand up properly, and hallucinated like crazy, seeing people that wasn't there. I ultimately blacked out behind my high school and got found unconscious. Mind you this was in January, so I'd likely have gotten hypothermia in addition to whatever the pills were going to do to me.
Was it hard to make the decision to do it? Absolutely not. I bawled my eyes out as I went to a Dollar General to get the pills and wanted to die right then and there after planning to for weeks.
Honestly, I'd strongly recommend not using over the counter pills alone, or really at all. The likelihood of it working is very low statistically and from my own experience, I'd likely have taken a few days to die.