I take the same amount of gliclazide as you. Everyone is different, but my body lets me know when i'm getting low, Usually at 3.8 i'll start to get a bit of a tingling sensation in my right hand, 3.5 ish my vision seems changes. I haven't had a full on hypo for a good few years, it's not a pleasant experience.
Do you get any indication when your levels go that low?