Tiny bit of air wont kill you, even in a vein.
If you still 3cc's of air into an artery, well, then you got problems but they will be over fast.
As far as her shooting you, you get what you pay for.
I rotate spots on my quads, as I cannot reach my delts, not enough to inject them anyway. Same with my glutes. I need to stretch more.
One thing that helps is I use 5/8th" 25 gauge needles, and I use an 18 gauge to draw up the stuff, then swtich to the little pin for the stick.
I am of the school of though that in muscle is no different be it 5/8th”, or 1.5” deep.
It is easy to find different spots on your thighs, and rotate between them. There are about 5 places on each thigh, and you can rotate them easily. Just get the area relaxed and sterilized, and use the Z track method. Having a tiny bit of air in the tip will make sure you are not looking 5mg with each shot as waste too. It goes to the top when you aspirate.
LoL “aspirate sounds like ass-pirate” I just noticed that. “He heh he”