Would this be an ulcer or something worse?

Well, let's see. I used to drink a lot up until about late April this year, ever since about 2 years ago. I'd drink a lot, and get extremely drunk at least two or three days a week. I would usually try to drink an actual alcoholic beverage, like something my dad had bought, but if he didn't get drunk enough for me to take a lot without him noticing, I would resort to listerine.(I am aware that alcohol found in mouth wash is not suitable for ingestion.) So, anyway, about a year and a half ago, in 11th grade, I'd started coughing up blood. I was too afraid to tell my dad at first, just because he would just get mad about how inconvenient it was because we really couldn't afford to get me treated. So, I left it unchecked. Now for my symptoms.. Well, there doesn't appear to be any rhyme or reason to when I cough up blood. I never actually vomit blood, just cough it up. It's extremely painful in my lower sternum, and a (comparatively) weak pain in my obliques.(For a point of reference, my obliques hurt like I tore a muscle, and the lower sternum pain is far worse.) If I'm coughing up blood, it's difficult for me to even stand, and if I resist coughing up blood, it hurts far worse. I usually cough up blood 2-3 days a week, sometimes 4, but it happens a lot during those days. It's usually while I'm in school, as well, and so I usually end up swallowing the blood because spitting it out or something to that effect would garner unnecessary attention. If I do end up getting seen in school, I usually make up some stupid excuse like I bit my lip open, and I actually proceed to bite my lip open if it's a teacher who sends me to the nurse. It's usually a dark red blood, although sometimes it's bright and pinkish.. uh.. what else.. Oh, if I get hit in my lower sternum, it causes a lot of pain followed by coughing up blood. I haven't been hit lower than that with much force, so I'm not sure if any lower would do anything. I don't really think it's an ulcer, because there's never been any blood in my stool, but I'm sort of hoping that's all it is. I don't know. Do any of you? Thanks in advance.