I'm fairly small (5'3" and currently 114 lbs, however I weighed differently at the times of these encounters) so regarding 8 mg being "on the verge of OD" this is my experience as someone who is of my size.
I've messed around with Ativan twice...I was prescribed it when I was eleven because of a seizure disorder, but never ended up taking it so I had a lot lying around (and lorazepam tends to have a very long shelf-life despite the on-label expiry date). The first time I took it I was eighteen years old and weighed approx. 102-104 lbs. I brought it to my friend's house after school and long story short took two 2mg pills orally. It was alright, I wasn't feeling very high but it was definitely affecting my ability to do stuff like think of words. My friends wanted to try snorting some, so I crushed up 3 more pills and divided it three ways and snorted the biggest line, so I had around 6-7mg total that day. It was pretty wild, seeing as no benzo had ever been in my body before that day (one of my friends wasn't affected at all by the approx. 2mg line, the other got pretty fucked up but had also eaten a lot of weed brownie so was probably mostly high from that), and I don't remember much. One thing I do remember is that when my friend woke me up because I had started to fall asleep whilst on the phone with a family member (whoops! that's a whole other story) my dream merged with reality and my friend's living room was all a swirling red pattern and I remember some shit about dragons.
The other time I messed around with it was a few months later, I was alone in my room, and the experience was completely different. I was probably about 120 lbs. at the time, maybe a few pounds fewer. I initially snorted 4 mg and told myself I'd see where things went and maybe crush up one more pill later. I felt pretty calm, but not in a way that one couldn't feel without drugs...I think that's the best way to describe it. Everything seemed really quiet though which was nice. I didn't feel too fucked up, just like if someone asked me to perform some tasks for them I would maybe have trouble with things that weren't completely basic. I decided to snort another pill, bringing me up to 6 mg. This had me feeling pretty damn good. I wrapped myself up in my duvet on my bed and it was the coziest feeling ever. I put on a good album on my iPod and just fucking chilled. I did end up deciding that I wanted more though, so I had 8 mg total that night. I don't remember a lot after that, but I know I felt so unbelievably cozy and it was the perfect feeling. I'd been pretty damn stressed out earlier that day and was dealing with untreated depression and anxiety at the time, so by contrast it was amazing.
The next day I woke up at 3 pm (my mother had tried to wake me up many times without success) and to my surprize was still being affected by the Ativan. I was supposed to meet some friends at the movies at 4 pm, so I threw something on and somehow got there relatively on-time. It's worth mentioning that I threw up before I left my home, but had not eaten anything. When I got to the theatre I just kind of stood zoned out until my friends arrived, at which point they immediately picked up on the fact that something was up with me. Apparently my body was crying - like there were tears streaming down my face and stuff - but I was completely oblivious to this. My friends decided to take me to the hospital and ignored me when I protested, but I didn't get upset because I was chilled tf out on these pills. I threw up again at this point. We stopped at the pharmacy in the mall we were at so my friends could ask the pharmacist what to do regarding my state and the pharmacist said I should go to the ER.
At the ER every person I spoke to assumed I was trying to kill myself when they heard how much I took, and were not convinced when I told them otherwise. In truth, when I was taking the stuff I just wanted more because it would make me feel more good than I was already feeling. In hindsight I'm pretty shook at having so many doctors assume I was attempting suicide, because I guess that means I could have accidentally done so. Apparently I got very close to ODing with the amount I took considering my size. I did end up fine, though. Didn't need IV or anything they just observed me for a few hours and gave me a psych assessment.
TL;DR Be careful when taking Ativan because it doesn't take a lot to OD, and your size plays a big role in how much you can handle. Some people are fine, others could get destroyed. "The verge of OD" is exactly how I'd describe it for me. Although I didn't OD, apparently I got close.