You have 3 injection sites on each thigh, and dont forget about your glutes. Dont worry about scar tissue. I would always use a 23guage x 1 1/2 for glutes. And 23guage x 1" for thigh. You should be good to go. Are you using nolva throughout your cycle. Prevention is better than cure.
Google injection sites. There is a site that tells you all of your available safe sites to inject in and actual pictures of exactly how to do it.
good luck bro