Overbearing when bf goes down on me

I'm a virgin and my boyfriend understand that and knows i want to wait until marriage before we have sex. We do oral and when he goes down on me I can't stay still and it gets to be overbearing. Like too much. It's not a bad feeling but I jerk in all these directions and he stops and I'll be fine. Does anyone have any ideas why I can't endure him going down on me? Like it feels so good but I make him stop after just a couple of minutes. It's upsetting to me and him as well because he likes doing it. Help please