I (19f) started shaking/trembling accidentally when my bf (19m) started making out with me, has this happened to you?…

Me and my bf have been dating for about a year (with a few breaks in-between). We’ve slowly worked on getting more intimate -because I’m super nervous and standoffish about having sex or being pretty sexual- due to insecurities. Last night I was fine with making out and getting more touchy than before but all of a sudden he noticed, I didn’t notice, that I was shaking. I couldn’t really tell and I wasn’t cold so I’m not sure why other than nerves…we stopped and started making out again and my lower half started trembling again. He thought something was wrong even though I tried to assure him I was fine but it just threw the whole mood off and we ended up going to bed