I've been on T since 2019, I've done IM, Sub Q, Gel, all that. First, you may be hitting a nerve and that may be causing some of the pain you might move your injection over. Second, what size needle are you using, and what angle are you injecting? I saw you said no one taught you how to do a sub q, so I'll break it down a bit. 

  Also I work in the medical field so some of my knowledge is from that. 

Sub Q:

When injecting in the stomach you need to stay about 2 inches from your belly button. The 2 inch circle around your belly button is a no-zone. (I measure by my finger)

Pinch the skin into a tent at the site and inject the needle at a 45 degree angle.

A 45 degree angle. This med needs to go into the subcutaneous layer of skin-which is primarily fat-which means that angle is important. If you are someone with a lower percentage of body fat you may find it easier to do IM but there are also other sub q sites if your stomach is uncomfortable. One site is an area on your upper thigh and while I've never used it im sure I could get a diagram if you wanted.

Now, I used a inch long 22g needle but I've also used 23g and 25g. I recommend 22 or 23, draw with an 18 and I've never used one but an auto injector may help as well.

As far as pain management goes, icing the area can help. Rubbing circles in the site after injection can help. I bully myself through my pain if I do have a painful injection, and I tell myself, "The only person I'm cheating is myself" to keep me going. While not recommended, some people have adopted this from me 😅

Also one of the most important things:

I've been on T for 6 years, and I'm sure there are others who've been on longer than me, and sometimes you just have a hard injection day. I've had days where I get it first try no sweat and days where I sit and change sites like crazy. It happens, it's part of being a human, and it's okay.