I've always had trouble with relative pitch and hearing music in general. When I was younger I couldn't tell you if it was a major or a minor chord I was hearing (when other people seemed to be fully able to), and very recently I didn't do much better than a dice at telling weather the interval I was hearing was an octave, a perfect fifth or a major third*. I'm also terrible at remembering how songs go.
I have trouble recognising consonance and dissonance, so most of the music making I've done so far is by strictly following the few theoretical "rules" I know, but that doesn't help much when it comes to impromptu playing.
Despite all this, I love music, and I would love to be able to play it on my own. I used to play the piano from reading sheet music when I was younger and the few times it felt like I was playing with my heart were absolutely amazing. Now that I'm older and playing around with a guitar (and more recently a harmonica) I feel like my lack of relative pitch is severely limiting me.
I don't want to think I'm tone deaf in the medical sense**, but I sure am darn close. What are the things I could do to improve this situation? I feel like a graphical designer with colour blindness and it's been haunting me since I was very young. Every music learning material seems to assume a normal relative pitch, i.e. they assume you can hear when things are dissonant and correct yourself based on that.
My dad has been making music all his life, my mother was an accomplished piano player, and my sister can pick up any instrument with relative ease. One of my highest wishes is to be able to unhindered create music with my dad before he passes on. Unfortunately, with his close-to-absolute pitch, he doesn't understand my situation and doesn't know how to help.
I understand I might not have said everything I should say, so ask any questions if you need clarification.
* It's not that I can't hear the difference between the intervals when I hear them in succession, it's just that when I hear them in isolation I have no idea which is which. It was the same with major and minor chords last I tested (which was a while ago.)
** According to The Internet™ I am just above "possible tone deafness," touching the "low performance" boundary in a tone deafness test. This gives me some hope.