Hi, me again and my "friendship issues".

So lately I got the feeling like I'm the "second best friend". I have a best friend, let's call her L. and she hangs a lot with another friend of hers: B.
They hang out a lot, and sometimes it makes me jealous that they hang out that much. When we go out with the three of us, B. demands a lot of attention from L., so it gives me the feeling like I'm just there for when B. isn't hanging around with L. Like I'm the second choice friend?

I know L. doesn't mean it that way and she probably hasn't noticed it yet. Problem is: I'm jealous at their "bonding" like they're really BFF's and would do anything together. And I'm just there...like...when nothing else is around.
I don't know if I should talk to my friend about it, but if I do, I don't know how she might take it, if she'd be mad or if she'd...I don't know. I'm also feeling very very down lately, but that's not for this topic, so I think it hangs a bit together.
Sorry if it sounds a bit confusing...