Domestic Violence

I think I may be an abusive girlfriend. My boyfriend of two years has told me that he has never had a girlfriend who hits him and that he's scared of me. Honestly I didn't think I was too agressive but I know that something's not right because why else would he have had a serious talk with me. We're both 18 and I'm only older than him by a month. I don't beat him up or anything it's just that occasionally if I get frustrated or mad I will push him away and bite him.. I don't want to hurt him but I feel like I have to be intimidating so that other people won't take advantage of me. I've told him this and he understands that I have been taken advantage of in the past by previous boyfriends and he thinks I'm just taking out my frustration on him. It's not fair for him to have to go through this because he is a respectful young man. I just don't know how to get him to understand my frustration. I've always been aggressive and this is the first time it's ever been a problem. I just don't know how to tone it down. 
​Have any of you women ever been told that you're to aggressive or abusive by your SO?
​I'm sure I can't be the only one...