Everyone deals with loss in some way and there's no "set" time as to when you'll stop feeling sad. It took me 2 years to stop feeling so sad about my father's death, and I was only 10 years old at the time (I'm 27 now, so it was years ago). All you can really do is continue to seek help from your pastor and friends. You are very lucky to have such a wonderful support system. After my dad died, I had no one to talk to (my mom hated him) so I ended up developing some issues and later at age 16 sook treatment for them, but I know you'll do better. Maybe you should put the pics away in a box for now, but don't get rid of them. You'll regret it if you do. I still have pics of my father, but I didn't look at them for awhile. You'll be okay.
I know how you feel. My grandfather was avery close friend of mine and he passed a few months ago. My whole family except my mom and I seem to be past the grieving stage, but sometimes I get really sad about it still.
Assuming you are a Christian, I would confide in your Christian friends and adults you trust. Create a support system and cling to it. Your friends and family will only be too happy to help and comfort you.
Go to God about it. Pray and keep up in the Word.
I know the loss of a loved one is really difficult, but you can get through it. God is in control- and He knows what He is doing. :)