Not getting breaks

I work in curbside, and I'm wondering how normal it is to not get breaks in this department? Our curbside has 10 people. I'm not sure if that's an average amount or not, but because of this, breaks aren't always guaranteed. Most days only 4 of us are working a day. The people doing the morning shifts coming in from 5-9 almost always get all their breaks, as they should, but it seems almost impossible for anyone who comes in at 10 or later to get all their breaks. And if you're coming in at 12:30 to do the closing shift, you can forget getting your last break at all. The last person to leave before the closer leaves at 6:30, which is about when the closer is supposed to take their last break, and since there's no one to cover them, there's no way to take it without leaving everything unattended. And whoever comes in at 10 and has to leave at 6:30 isn't guaranteed their last break if there's still picking to do and they're the only picker left besides the one who has to run the back. This is one of my least favorite things about working in this department at my store. My TL also seems to have a problem with us taking breaks sometimes. She'll often tell me we're too busy, so I can't go on my break yet. When I tell her I'm going on my break instead of asking, she yells at me and tells me I have to ask. I guess I can't always go on my breaks when I'm scheduled to take them??? Can she do that?