how bad is "too bad"?

I'm about three weeks in to lexapro (week and a half at 5mg, week and a half at 10) and still having a rough time with side effects. I'm extremely apathetic, have been dealing with sporadic suicidal thoughts, nauseous, and have lost ten pounds. I spoke to my doctor about this and she seemed fairly concerned about the apathy, and told me I can think about stopping if it gets "too bad." However, I also know I'm still in the rough period (and hopefully almost through it). I'm not sure I want to quit now and have this all be for nothing, but I'm also not sure how to tell when I need to call it quits. Other people in my life have mentioned the weight loss and asked about it, and I'm not sure how concerned to actually be about this. For better or worse my anxiety is completely gone (I'd normally be concerned but now I'm blank), but I'm wondering if this is something I should be worried about? Or do I continue to stick it out? How bad is too bad?