Why was I so happy yesterday night but so depressed today

I feel so horrible and guilty, I've been pretty depressed lately and I don't know if i'm doing something wrong or not but my mom keeps getting mad at me, and I keep getting snappy with her. The other day she tried to take a selfie with me and I kinda got mad at her because it was in front of everyone and I didn't want to get anyone uncomfortable if they were accidently in the background so I told her stop in a kind of mean way. She stopped talking to me for the rest of the night and she keeps bringing up how disrespectful I am. I tried to explain to her I didn't mean anything mean by it?? It's triggering my OCD so bad and tonight i'm going to see a band I really wanted to see, and i'm super afraid shes gonna start bringing up how mean i've been lately. I've been really depressed and upset because of school and how much work their giving me, and I've been in my room for mostly more than 10 hours a day doing nothing but watching TV because I can't bring myself out of it, I don't know what to do anymore and the guilt of me possibly being a mean and aggressive person is haunting me.

Last week was a lot easier for me. I felt like thoughts didn’t control me and my actions as much as they did earlier. Today was really hard for me and I feel like I’m starting to lose hope again:( I can’t take the thoughts and the feelings that come with them anymore. I feel like I have failed and I’m never going to be happy again.

I’ve been in a really difficult situation recently and this weekend I’ve been looking forward to for ages. I had a concert and then nights out planned with my cousins. But I’m a tad bit older than them and they’re a lot closer in ages, as are all their friends from uni, so I’m kinda just stuck here with nothing to do. They’re off flirting with people their age and dancing and I’m getting no attraction or even attention (not in an attention seeking kinda way just an I’m lonely kinda way). At the concert they left my 5 or 6 times to go to the toilet and get drinks, when I went to the toilet I went alone. I was left alone to the point people around started to notice and I had one guy say “left alone are you? You need to get better friends” I just feel very left out. I’m a lot older than them and I know I have to keep a mature head but I’ve already fallen into a pit of depression recently and very very low self esteem to the point I barely wanna go out in public, that I’m now sat here all anxious and in a really bad mood. I don’t even know exactly why or when it changed but last night I just snapped. My sister was off meeting new people, my cousin was dancing with creepy men, a guy I found attractive was more interested in my cousin, she started dancing all provocative on him and I was just kinda there. I then had people asking me if I was neurodivergent and bisexual which just sent my ocd spiralling and nobody quite understands how horrible it is to be in my head. There was this lovely guy saying how amazing stunning and beautiful I was but it kinda just made me go “you’re saying that because you feel bad for me, because you know they’re getting all the attention and I’m this ugly duff person on the side”, it’s insanely exhausting. I’m tired of it now. I don’t wanna be in a mood anymore but I can’t seem to shift it, I’m stuck