Hey Kelsey, firstly, welcome to the forum.
Secondly, I'm so sorry for the loss of your brother. I can't imagine how devastating it must've been. You two must have been close if you felt very lonely after it happened.
I think, most of the time, people, be it our friends or family - they don't know how to react or treat you when they know you've had a loss of a loved one. In my case, when my father passed away, my friends didn't mention it at all after the funeral, thinking that I may not want to talk about it or that talking about it would upset me but the truth was, I would've welcomed the acknowledgement of what I was going through.
I think we can't expect others to understand our situation of loss, or understand how exactly to behave around us because most of the time, they have not gone through a similar experience and so do not know how it feels like. What I did was to remove myself and distance from everyone around me but I don't think that is a good idea. Best is to speak up, if you really want to talk about it with them. If you don't want them to be sympathetic with you at all times, then talk to them about it. Allow them to realise what they should or should not do in order to help you in this grieving process.
Once again, my deepest condolences to you and your family. I hope that you can get through this difficult period with ease and sufficient support nonetheless. You can also express yourself here and talk about it whenever you feel like it, there are quite a number of us who knows what it's like to lose a loved one to death. Sending you peace and best wishes. *hugs*