Should I send a brag sheet for my counselor rec. letter?

I second @izziann suggestion of setting up an initial get to know meeting. You get a sense of how well they actually know you and it can be a good opportunity to put a face to your name if you don't see each other often. If you can set up reoccurring meetings to check in on goals and make sure you're on the right track that would be a good thing too.

In terms of a brag sheet I think it would be fine to give them one. You can mention the fact that you wanted to provide it since you haven't met as often as you would have liked. Keep in mind just because you give one to them it doesn't mean they'll use it. If they have so many students where they barely know you they might just churn out LoRs as fast as possible and include only the most basic information. Make sure to find some good teachers, advisors, or mentors for your other LoRs to possibly make up for a potentially lackluster one from your counselor.

This is a good question :)

I would suggest setting up a get-to-know meeting with your counselors, just to get a feel for where you stand in their minds. Next, I would discuss your scholastic accomplishments with them. (Yes, it may be a bit awkward, but I think that you would do better putting yourself out there.) If you really think that a rec letter or bragsheet would be beneficial, you can ask them. I suggest asking them in person, because they have a more likely chance of saying yes.

Hope this helps :)