Nervous/ Insecure

My boyfriend and I have been together for awhile. Obviously we do sexual things but when it’s actually time to DO those sexual things I get sooo nervous.. I’m honestly not sure what the issue is but when we’re in foreplay mode, I can’t stop thinking about how nervous I am.. or when it’s time for him to go down on my I get so insecure convincing myself that there’s a smell or he won’t like it when in reality there’s nothing wrong at all. I have so much potential yet don’t know what the issue is :/