i've been on C for almost 6 yrs and have done well.
it sounds like your site reactions are normal.

i remember getting them for at least a yr.
then it got a lot better.
i use the autoject. you might have to play around with the depth setting to make sure you're getting into the sub Q fat area. i ended up going a bit deeper and it helped a lot.

also try to ice the area after the injection for a few minutes. like a bag of frozen veggies or an ice pac. shared solutions will mail you an ice pac too.
the next day you might try some gentle massage. or try some benadryl cream for the itching.

i really think this will improve for you. hang in there.