Are you using the auto injector? or going manual? it makes a difference.

Injector rules
If you can pinch at LESS than an inch go for 4
If you can pinch an inch go for the 6
If you can pinch a fat inch with a nice pad go for 8
If you can pinch 2 or more inches go for 10

If you cannot bring up that inch, or keep smacking muscle in that area, you may have to shoot manually, and use a 45 Degree angle.

I go long periods of time without using my arms. They stay quite painful for a long time days/weeks after using them. I just do a double bum bum shot. Lots of real estate there.

I am 98% manual now. I only pick up the auto inflictor when the husband isnt home to help on bum bum days.

I dont stick to that chart. I stick to MY body, and where MY fat lives. There is NO fat on the front part of my thighs, only sore thighs if I poke them. I lean way off to the side, sometimes headed towards the back, cause that is where MY fat lives. On my hips/bum area, I use the full side wall. I dont just stick to that small area indicated on the chart. I go from the love handle all the way down to the upper thigh area. Tons of fat parts to pick on.

If you stick your thumb on your hip bone, swing your fingers around towards your bum, or pointed backwards. Spread out your fingers. That is a great fat area, with a solid fat pad to pick on. I go as far back as those finger will stretch, but wont go further. I have a friend who shoots her whole bum, upper, lower, middle and it scares me!

As time marches forward you will learn about your body and what works for you.

Hang in there.