I don't think anyone here can tell you that, it's something you will know inside, as time passes.
I do believe when a life is cut short, that soul will come back to finish growing or teaching.
I also lost a loved one, when he was only 10 yrs old to Cancer. I never had dreams or anything of him, but I was praying and talking to God to give me a sign, that he was okay, many years later.
Right after, I looked over to the tub, and there were a bunch of shampoo bottles...and I didn't notice this before....but the name on the bottle was my loved ones name...and the last three letters of the name are SON, and it had three small dots above the SON part of his name on the bottle..
I do have a son who acts and looks like him. Even my grandparents and great grandparents say he looks just like Jason. I have picture where they look like twins, but obviously my son wasn't born until 8 years after he died. That little boy also loved me very much. That was also the name on the bottle of the shampoo that was sitting on the tub with several other shampoo bottles, that I didn't pay attention to the name when I bought it, I ordered it online based on reviews.
Coincidence, I don't personally think so.
I,do know there is life after death....but I don't know what each soul chooses to do after that. But love is the ties that bind, so your brother may have just came back to you as a son. Soulmates is what it is. Losing a sibling is probably the hardest thing to go through next to losing a child. Your story touched my heart, your brother would be my age...and I have children his age now. I say pray and ask for a sign...but then again, if you are asking, you probably already know on a spiritual level.