Here are the "rules of thumb" that have worked for me.
I have used Sus 250, Test, Prop, Test Enan, EQ, Deca, Winny and Tren for injections. Primo is a whole other story.
For glutes use a 23G, 1.5" syringe and push it in all the way (only push it it in 1" - or 2/3 of the way - if you don't have much fat on your glutes).
For site injections I use a 25G, 1" syringe and follow the same protocol as I do for 23G syringe injections.
I always take about 30 - 45 seconds to slowly push the oil in and I never wiggle or let the syringe drift in or out even a millimeter!
You must keep the needle in all the way, not wiggle and push the oil slowly into the injection site. A steady hand is often key to whether the injection will be painful or not, but not always.
It sounds as though you didn't shoot your Sus 250 deep enough into the muscle and a knot formed in the subcutaneous fat layer.
Also why are you doing Test Prop AND Sus 250 at the same time? Wouldn't you want to switch from Sus 250 to Test Prop in the last 2 or 3 weeks of your cycle to better control your Test levels at the end? it seems like a waste to use the Test Prop now as long as you have enough Sus 250 on hand. Just curious.