Iam solving total problem. u can check where u made a mistake.
what ever u told is correct. In the the next steps u may did some mistake. Here is the complete solutions.
Since the initial slope is -20 db so it represents a single pole 's' and it crosses 0db at ω=12 rad/sec
so the transfer function is 
and at next slope is -40 db/decade and it starts from ω=1 rad/sec and there is a pole at ω=1rad/sec
∴Trasfer function for that line =
and next slope -20 db/decade and it starts from ω=8 rad/sec it indicates that there is zero at ω=8rad/sec
∴Transfer function for that line=
an next slope is 0 db/decade and it starts from ω=60 db/decade it indicates that there is zero at ω=60rad/sec
∴Transfer function for that line=
and next slope -20 db/decade and it starts from ω=400 rad/sec it indicates that there is zero at ω=400rad/sec
∴Transfer function for that line=
so overall Transfer function is 
∴T/F =