Q: How come I am not getting any free space after deleting photos from my mac?

So, I am frustrated now to say the least. For the past few days I've been trying to edit a youtube video, but I'm not being allowed to because I don't have enough free space. The thing is, nothing happens when I delete photos and videos from my photos library. I've recently deleted at least 500 photos and many minute long videos, and yes, I delete them from my recently deleted album as well, but to no avail. I've restarted my laptop many times and sometimes that give me a couple hundred megabytes, but that's significantly less memory compared to what I've deleted, and is only enough to insert one clip into my video before I'm told I can't edit anymore. I've already deleted all the apps that aren't required by OS X and at this point I'm at a loss for what to do. I've tried seeing what others were suggested to do, and it seems like everyone else's problem stemmed from not deleting their photos from the recently deleted album but I do every time. I didn't have this issue with iPhoto and now I'm really regretting updating. Could anyone please help me with this issue? Thank you!