Car Accident - At-Fault?

Hi,

I was in a car accident about a month ago and my insurance company
determined that I was more than 50% at-fault.  I just got my notice
that I can appeal the determination but it requires $50 first so I
want to know what anyone thinks.

I was traveling parallel to a pretty big truck with my car being next
to his cab.  We were traveling on a ramp to go onto a highway.  The
ramp was two-lanes but the lanes weren't marked.  I was in the right
lane and my lane was ending as the ramp merged into one lane.  I had
my blinker on and sped up to pass the truck.  As I ended up in front
of the truck, the truck hit the back quarter of my driver's side.

I realize that there are a few things against me...there was no damage
to my rear, it was my lane that was ending, etc.

What I have issue with is that at the point where I was hit, there was
really nowhere for me to go because the lane was narrow.  I also don't
think that I hit him while I was merging but rather he came alongside
after I was 95% completely in front of him.  The lane at that point
could fit about 1 1/2 cars and I think that the truck driver
essentially tried to keep going thinking he could get through on my
side.

I know my case may not seem too strong.  Does anybody think it's worth
trying to appeal?  Thanks.