At your age, it's a combination of 'sucking it up', getting 'mad as h$ll' and allowing yourself to grieve. Structure can support you while you regain your balance. This is definitely something you don't 'wing'.
I'd suggest writing (in long hand) about cherished memories, your childhood, family times, fond rememberances, etc. At least a couple pages a day. This process will help you 'get it out'. Out of your Mind & Heart and onto paper. Don't edit. Don't hold back. Just write, remember and grieve.
Exercise is also important. You're not supposed to have 'fun' at this stage. It's a time for grief. That doesn't mean not taking care of yourself though. Self-care is very important. Your esteem, paradigm and brain have suffered a massive loss. Like part of your experience/self/family has been torn out. Because it has.
Animals can be a great source of emotional support during such times.
The reason 'your family is no longer who they used to be' is because they aren't. A key member of your family has died and such, all remaining members are forced into an area, and feelings, that are very uncomfortable, destabilizing and insecure. All may not handle this immense stress well.....
When I was 2, my Mom woke up from a radical mesectomy expecting nothing of the sort. She fought for 6 yrs until she died at 44, when I was 8. The old man was never the same. After a too-fast-disaster-of-a-second-marriage to 'restore himself', he died 9 years later, shortly after my 18th b-day during my freshman year of college...three days after Christmas.
I spent the next 11 yrs of my life in various lawsuits fighting his second wife, a corrupt CPA uncle and his incompetent lawyers. FUBAR. All around. FUBAR.
I survived though, healed, recovered, and gained strength & wisdom. However, what worked for me, may not work for you. I doubt your family was such a disaster as mine turned out to be. You'll have to find your own way, your path through the pain. Your family may be a hindrance or a help. Hopefully you all find a way to remain a family rather than careening off into a ditch.
Therapy can help. Religion can help. Traveling can help. Writing can help. Animals will definitely help.
One note of caution: Be very careful who you sign on with as a counselor and in whom you place your trust. You're very vulnerable, in shock, dazed and confused. Thus easily manipulated & deceived. So while exposing your pain, you must also protect yourself from situations where your best interests are not primary. A very fine line indeed.
I'm LONG removed from both parents death. Major difference. I'm an extremely late bloomer because of it. Talk about The Road Less Traveled.....wow the tales I could tell....
Families are like one of those mobiles that hang from a ceiling. Some are more balanced than others. However none are immune to being upset when one of the main counter-balancing members is suddenly removed. It sets the whole thing in motion and out-of-balance. Regaining balance takes a long time.....
My condolences for your major loss.......