Obsessing over death without actually being suicidal?

So after being diagnosed a month and a half ago, I've been taking 50mg of Lamictal and I've been doing pretty well all around. The past few days, though, I've started to slip again, and today I've been feeling more depressed than I have since I first started taking medication. One of the recurring thoughts I've had a lot lately is about death.

I'm not suicidal. I know that much for a fact; I've been suicidal a couple of times in the past, once severely, so I know what it feels like, and this isn't it. I don't want to die. But for some reason, thoughts of my own death have been occupying my mind a lot these past few days.

The other night, while I was lying in my bed, I kept mulling over how easy it would be to get up, grab my pills, down the bottle, and go back to bed. I didn't want to actually do it and I wasn't afraid that I would; I just couldn't stop thinking about how easy it would be to do it. I ran over how I figured the situation would play out the following morning: at some point my sister or someone would realize I wasn't responding to texts and wasn't out and would ask my roommate to check on me, who would find me dead.

Earlier I kept picturing myself standing on the roof of my five-story dorm (which I don't think is actually accessible without a key), looking down at the ground. Maybe some people would see and a small crowd would form, police would be called, someone might come up to try and grab me and pull me back. Maybe I'd just take a step forward before they could do it.

Sometimes the thoughts aren't even related to suicide. I might be crossing a street and think about suddenly getting hit by a car, like a couple of students were back in October. Maybe there would be a shooter (something which has never happened at my university) and I'd get shot to death while walking to class.

No matter how the scene plays out, though, I always start to obsess over what the aftermath would be like. My family would be devastated. My friends would be shocked. I'd be featured in next month's Silver Taps, a monthly ceremony dedicated to students who passed away in the previous month. My therapist, who I've only been seeing for a few months and who has never really seen me depressed, would be confused. And once the thoughts start, it's really, really difficult for me to rein them in.

I don't think these thoughts are entirely unprecedented. Death has been a pretty prominent theme of my semester so far, considering a good friend of mine was found dead from unknown causes in her dorm room at the beginning of February, and my grandfather died suddenly exactly one week later. Whenever I walk past my friend's dorm, which is right by the psychology building (psychology is my major), I think about how that was the last place she was ever alive.

But I don't want to die. I have a lot to look forward to, and for the most part, I'm optimistic about the future. In just over three weeks I'll be moving back home for the summer, I'll get a job, next semester I'll be living off campus with a close friend instead of three random roommates in a really nice apartment complex, next year I'll be getting a tattoo I've been wanting for a while now. I don't have any plans to take my own life, and if I were faced with a life-or-death situation, I truly believe I would fight tooth and nail to keep living. But these thoughts are becoming too frequent and detailed for me to just keep dismissing them as ordinary intrusive thoughts.

Has anyone else had similar obsessions? Could it be a result of my medication? I have an appointment with my therapist next Wednesday but I think I'm gonna call him and ask to reschedule it for sooner because I need to talk to someone about this. I might try to move my psychiatrist appointment for my two-month followup from the beginning of May to sometime sooner, too, in case this is a result of the medication.

Sorry about the wall of text. Once I started typing I couldn't stop. I think I needed to get this out.