Hi, unfortunately bruising is not unusual. I guess it could be called normal.
From time to time I have a patchwork of bruises on my tummy where I inject. I'd recommend using the shortest needle that woks for you, and then applying firm pressure for 30 seconds or so after injecting to prevent bruising.
However, from time to time, it may be unavoidable. In this case, just accept it's part of the game.
Best wishes to you.
Very common and don't be to worried just alternate places you do your site for a while