Tempers and other things aside, I had a chance to look at your “Flickr” account and I wanted to jump in and give my 2¢, but didn’t have the time.
Yes, your Flickr page/account/portfolio should not be your go-to portfolio, but that being said, it does make things easier to share and display without having a dedicated website. Either way, who really cares,as long as we can see what you are trying to display.
In my humble opinion, I did not care for your processing on your later shots, but that’s just me. I am referring to the HDR look. To me, making a punk band look grungy adds to their character but it didn’t come through with the processing style you went with, at least to me anyway. That being said, the black and whites do the band no justice either. From my experience, mind you, B&W processing is a go-to when you are trying to convey texture, depth and feeling without the disruption of color. This is why you see so many dramatic portraits done in B&W. For the band, it doesn’t fire for me, but hey that’s my opinion.
As for your niece, she is a beautiful girl, coming out of her shell to pose in front of a camera must be a very new experience and a big step forward for her. No matter how the photos come out, keep encouraging her and try to ease up and have her [and you] relax, have fun, that’s when the best photos will come out.
As for the posing, that just takes time and practice. You can go online and get several “free” ideas for techniques like this one HERE, there are tons available online if you search hard enough, but the key is to relax and have fun with it.
I see some small technical mistakes that are easily correctable, but that comes with time and shooting.
Out of all of the photos on your flickr page, I like this one the most. It’s simple, clear, in focus and straight to the point.
Another thing I see is that you like to shoot, keep it up and keep sharing.