Hi, WeasleyTwins here to review as requested!
For your first fanfiction, I believe you are doing good. Many first fanfictions are all dialogue and no description. But here, you've really put in descriptions and tried to set up the scene for your readers, so well done!
So, I'll just jump right into things and discuss the interest of the chapter. Honestly, I think that people are starting your story and then not continuing because of the grammatical mistakes and typos - spelling errors, tense confusion, and other such things. We're all not grammar geniuses, nor do we catch every mistake. I think that if you went over to the forums and requested a beta, your beta could help you smooth out these kinds of errors. I believe if you fix these types of grammatical issues, your chapter would be much easier to read and readers would be more likely to continue. I know that many readers on this site look for proper grammar because it makes for a smoother read and also so that they can focus on the plot and characterizations and overall feel of the story.
As for believability, I think what you've got is very plausible. But I would remind you to keep the characterizations and descriptions consistent. For example, at the very beginning when you describe Ginny's reactions to the tragedy, it seems a bit mixed. At one point Ginny says she doesn't want to be upset and at another she's very choked up. Of course, Ginny would be very distraught at the death of her brother. However, what I'm trying to say is that in your descriptions and dialogues, remember to convey this idea that she wants to be strong, but really can't be - you don't want to present a contradiction to readers.
Also, if you are planning on sticking to canon, remember to be careful with characterizations. I like how you've written Ginny because you've made her character your own, it's Harry that I'm a bit concerned about. It's only because I read the series and know Harry inside and out, but I do have a suggestion. Harry really isn't one to tell someone his emotions in depth. He will tell them, but not in an extensive manner. So, during the section with his POV, I think that some of the dialogues are a bit loaded. The descriptions of his emotions are fine. It just seemed to me that Harry wouldn't be that verbal with his love. I definitely think he would say "I love you" but maybe not in so many words.
I really liked your ending - I thought it was creative. Overall, for your first fanfiction, I think you're off to a decent start. I hope I wasn't too harsh. Please feel free to re-request anytime!
Author's Response: Thank you very much. The first chapter I've re-edited over and over by now, but it still seems like I need to go over it. I can see how I would been a little inconsistant with Ginny's character, and then descriptions. It's tricky though, because I do want to get across that she's trying to be strong, but can't be all the time. So I'll have to go over it again to make sure that's happening like I imagine it.
Harry has been trickier than I thought, and yeah I can see some of the dialogues I put in are loaded, not just with Harry either. I've tried to stay away from it, but as a somewhat new writer, it is a hard habit to get out of.
No you were definitely un-harsh, just realistic, and that is super helpful when writers want to improve and not just write whatever comes to mind. Which I've definitely done my fair share of :P
Thank you for the tips!