Not really sure what to do, and I want some advice please

I'm a younger teenager (13-15), and my mom recently passed away due to health complications, so now I'm left in my house with just my dad (52) and my older brother (20). I'm currently doing home school, but my dad, my older sister (30)(C) and I are all talking about me going back to an actual school to finish out high school. I'm behind in my home school work, and it stresses me out often cause I can't catch up because the system keeps going and I can really only catch up when there's breaks in the calendar.

I do have another older sister (23)(B) who lives right across from us, so sometimes I go over to her house to see her and her cats, and usually I go over to my other sister's (C) house to do my home school work during the week.

When I was younger, I was diagnosed with a few things, such as Major Depressive Disorder (MDD), Social Anxiety Disorder (SAD), and Generalized Anxiety Disorder (GAD)- I know that these are probably common and normal for others around my age. I'm in counseling and am planning on taking medication soon, so that's not really a problem, but I thought I should mention that just in case.

My sleep schedule is completely messed up, like most nights I stay up until I need to get ready to go over to my sister's (C) house for school, which is around 5 or 6 in the morning, since sister(B) has to take me over there around 7 on her way to work. Sometimes I'll fall asleep, but then I'll sleep through my alarms and then I don't go over to sister's (C) house, and end up sleeping most of the day.

I'm also in a home school band, but I haven't been going lately since my mom passed.

I just don't really know what to do, and just kinda want some advice on what I should do. I want to be social and stuff, but it feels really hard and like i'm not completely sure where to go or how to talk to people or initiate conversations. Just kinda want some help please.