Where can I use a syringe other than my belly if I have really low body fat?

T1 less than 2 months after diagnosis - I’ve been injecting into my stomach for the entire time I’ve been diagnosed but it’s starting to get really sore and hurt as I’m using about 5 needles per day. I want to use a different area of my body but there’s really no fatty places anywhere else, I’m afraid I’ll inject into muscle and it will be painful or won’t work. I need an alternative