What?

IDK what to do. I can't tell if some issues are because of me and my outlook on people from past experiences I've had. Or if it's actually because of the other person. Basically, I just get depressive and upset for no reason. I could be having the best time of my life and all of a sudden it just hits me.
Sometimes I have arguments with my boyfriend because I feel like I don't matter to him. Inside I know that he cares about me alot, But, I also feel like he deserves a better person to be with. I feel like I'm wasting his time most of the time. He has really bad ADD, some days he's ok and easy to talk to. Other days, he has like a 10 second attention span. 
I know my bf has ADD issues. But, I'm so used to people not caring about what I have to say alot of the time. It just feels like he doesn't care to listen, even though I know about his problem. Then I get depressed and feel alone. 
I'd like to get help for both of us because his ADD effects his job and life everyday. We'd both just like to be more functioning people and have a better relationship.