@AnotherPenguin I echo many of the sentiments already expressed here: stay focused, work hard, give yourself credit when it's due, fly GA, apply to UPT, etc, etc.
However, like @Danger41 suggested, I recommend you reach out to someone -- an unbiased and objective third party -- who can help you work through your feelings of unhappiness and disappointment. Call MilitaryOneSource (800-342-9647). They offer free non-medical counseling -- 12 sessions, no questions asked. No cost, no strings and no one will know, unless you tell them. As a pilot, I was afraid it would impact my ability to fly, but that is not the case. They'll hook you up with a local professional, unaffiliated with the military.
Call me a triggered snowflake, but I'll join you in saying, it is very hard to suffer the pain of an indifferent, or worse, taunting family -- both as a child and an adult. Being the best RPA pilot you can be might assuage you for a bit, and we can regale you with the merits of your mission, but at the end of the day, your dad and brother -- two people whom you look to for approval -- will still dismiss your work. I had everything I'd ever wanted, but was seriously dissatisfied until I realized, happiness is a personal choice and no sort of achievement would ever make my parents more interested in my life. It's tough -- and I hope if and when you have kids you'll love and support them -- but I think you'll feel better when you look for validation from people who can and want to give it.
If anything, it's therapeutic to bitch to someone who is trained to listen, regardless of the subject. There are also a ton of great bros in the AF. We've all been in your spot at one time or another. Lean on them.