Im a relatively occasional drinker (once or twice a month). However, when I drink it's not really a light drink. I usually aim for the Yellow Line and try to make it to the Red Line but normally dont drink enough to make it there (I know when to stop...most of the time)
I believe there are 5 stages...for me anyway... (I am not changing any of yours, except I am calling your 'Yellow Line' the 'Orange Line' and putting my own 'Yellow Line' in)
Green-line:
At this level, you have had 1-2 beers/drinks and you can feel that you are drinking, but there are no adverse effects to your drinking yet.
Yellow-Line:
At this stage you have had a few, you are starting to feel the effects such as 'lag' in vision when turning your head and time seems to be slower (I always smile when I look at my watch and realise it's still early). However, you still feel like yourself and are still in control. You are happy at this stage

...I also believe that this is the longest stage (Red might
feel the longest but to me the yellow-stage lasts a while)...However, this is the stage where you make the decision to stop now OR you decide to drink more and push yourself to the Orange and Red lines.
Orange-line:
At this level, you think more clearly/better, and you are more social. You can carry on more philosophical conversations and understand more philosophical conversations at this level, than when you are normally completely sober. You are also super talkative and your social inhibitions are neutralized almost entirely. The only draw-back to this level, is that it is difficult to maintain, because it is very easy to slip into red-line.
Red-line:
At this level, you have had way too much to drink. It is very likely that you will throw up or pass out soon. Either way, at this point, you are unable to think clearly/quickly, and whenever you talk to someone, you find yourself repeating yourself often and talking loudly. It is unlikely you realize you are talking loudly, but others will notice this right away. it is also very unlikely you are able to carry on intelligent conversation at this point. The "generic" drunk signs are also prevalent: difficulty with spelling, walking, talking, inability to stay still, drowziness, etc.
Black-Line:
This is the final line, you have just thrown up from too much alcohol or you are about to pass out. There are what I believe 3 outcomes to this stage, depending on personality and gender.
1. You don't want to socialize or talk to anyone. (unaggressive, applies to both genders)
You may be embarrassed about throwing up or drinking too much. (This is me when I "black-line")
2. You want to pick a fight. (aggressive, mostly applies to Males)
You are angry for some reason and want to pick a fight, most of the time nothing happens or you end up picking a fight and likely will lose. Maybe you just kick something cos you are pissed off. (observation of other wasted people)
3. You are over-emotional and start crying (unaggressive, mostly applies to Females)
You start crying for almost no reason or telling 'sad' stories that make you tear up (when they aren't even that sad) and make others roll their eyes at how pathetic you look/sound/are (observation of a few of my friends)
So yeah, this is my extension to your levels of drunkenness. Yours are perfectly reasonable and all fit in. I just think that you were missing a couple of levels. Personally, non-drinkers at most stay at the green line. Most occasional drinkers only get to the yellow-line and try for the Red but mostly miss. Alcoholics go for the Red every time and many times slip into the Black line.
Im only 20, so are my friends, but in my short experience I believe there are 5 stages of drunkenness. I know this post is long but I had fun writing it

I think I will try to "black-line" this Friday! Or at the very least get to Red Line. (it's a friends 21st party and I need to get drunk cos its been a month and I am back at uni and pissed off about it already, definitely need to drink!)