Right now, you're only doing body sparring becuase you're new and he doesn't want you taking unnesecary shots while you're still learining. Use this training to focus more on your footwork, movement, finding your range and putting your punches together in combination while maintaining your balance, and don't focus so much about actually landing punches. It will be difficult to land if you can't hit to the head and the guy only has to block his body. It's just a way for you to get comfortable moving around against an opponent in a safe manner, not about who's landing and who isn't.
Once you get to full sparring with headshots, then you can practice setting up body shots by going to the head first to raise his arms and make an oppening.