So-called friend always leaving me out?

My “friend”/roommate has a habit of making plans with her other friend (s) pretty much in my face or when I’m within earshot, and not even bothering to ask me if I’d like to come along too. For instance, towards the end of last semester, I’d mentioned wanting to go to The Cheesecake Factory to celebrate the semester being over; then a couple days later, I happened to open the refrigerator to see a to-go box from there. When I playfully asked her about it, she said that the previous night, she and some friends “just ended up there”.

Then just last night, when I was pretty much within earshot, she and her friend “L” (the three of us are living together for the summer) decided to go get pizza together w/o bothering to ask me if I’d like to join, when just 2 or 3 days ago I suggested getting pizza for dinner because no one felt like cooking, but we ultimately didn’t get it. And every time she does this, it’s like she tries to lower her voice so I won’t hear their plans, making them feel obligated to ask me if I want to come too (which is also the reason why I don’t “invite myself”). Always going to the grocery store without me when I need to go as well; I’ll mention groceries, then go to work the next day for 8 hrs., come home, then a couple hours later they come through the door with hands full of grocery bags, leaving me to have to spend money on Lyft to get to the store while she gets rides for free with “our” friend. She could’ve texted me and asked if I wanted to go when I got off…

I don’t want to say anything because she just had drama last month with another friend and said she feels like every time she turns around, somebody’s mad at her. But I’m mad because this is something that’s constantly happening. I don’t want to come off like I feel like I’m supposed to be invited everywhere she goes, but at the same time I just feel like it’s rude to sit there and make plans in somebody’s face and totally exclude them, but claim they’re your friend and act normal.