Issues With Finishing...

So my boyfriend and I started doing sexual things a few months ago. It started with over the clothes touching and that got him hard really quick. A few weeks ago I gave him a blowjob for the first time and he finished that time and the following 3 times. The problem is that after a while he just stops feeling things... This has made me incredibly insecure and we’ve tried things and communicated about it but it really isn’t helping. I recently touched him and he said it felt good again (not as good as it used to but it’s a step forward) but he couldn’t cum from it. Now I do some things but he helps me out. I am just so scared to do anything again (he understands this) because it really made me lose confidence in myself. I was wondering if anyone had advice on how to help because he pleases me so well and I want to do the same for him. (We haven’t had sex yet and we want to wait a little longer for this. We have almost been together for a year though but we have a certain age we want to wait until).