Do you not think that the lowest point of the crashes of 2011 (October) and 2013 (April) should indicate where the bottom trend line is? I find it difficult to believe that both of these crashes - which were very extreme - didn't hit the bottom trend line.
I see bottom trend line as the connection between lowest points in BTC chart (together with tops forming the channel we are currently in). Imho connecting low points following each bubble is not crucial for general trend, these are just corrections and therefore can only tell something about the potential low of any future post-bubble correction. This is of course just my opinion and (unfortunately) I don't own the patent for truth-seeing :-)