Feeling hopeless and lost

Finding this site today has given me some relief. I am currently undiagnosed in the process of going to a new doctor this week to see what can be done. My brother and father both are diagnosed with ADD. My parents divorced when I was two and my mother always thought I was strong enough to take care of myself and put all of her time and effort into my brother. I experienced many symptoms of ADD as a child and teenager but it was always just brushed off as "being a teen" and so on. I never really developed coping mechanisms or just had the comfort of someone being there for me. I met my fiance' my senior year of college. We have been together for about 3.5 years now and it has been a roller coaster. I was really trying to work on myself around the time we met: building confidence, being self sufficient, trying to work on my issues (which at the time I hadn't suspected were those of ADD). 

Reading all of these posts I see word for word things I have been dealing with and things that I have been doing that I didn't understand that have steadily been tearing apart my relationship. My fiance' is a very intelligent, very logical, straight to the point person. I relate to everyone that I have seen on here that has trouble focusing and even answering a yes or no question. Sometimes even understanding what I am being asked even if it is something extremely simple. It is often that hours later I understand what was being asked and that I knew the answer and beat myself up for not being able to answer. I also have a problem where my mind starts racing and I can't get everything straight so I will impulsively lie so that I get an answer out. Even if right afterwards I realize what I have just said is completely false. It is not that I am intentionally trying to hide things or hurt him, but it comes off that way and builds anger and resentment. I also find that in a lot of situations I get extremely defensive, emotional, and it has become quite common for me to backtrack and say "oh, well that isn't what I meant". He says that often times he feels that he now has to walk on eggshells with me and hates bringing things up to me or having a conversation because I either break down, freak out or just completely shut down. 

He says it often times comes off as I don't care and that I am very irresponsible. It is very hard for me to complete normal, mundane tasks. Even things such as laundry, cleaning, or even running to the grocery store. Listening is also an issue for me. It isnt that I dont care, it is just so hard for me to stay focused a lot of the time. I really do love him, an interested in our lives, and want to move forward in a positive way. Keeping a job for me has been difficult, I haven't been able to keep one and be a reliable financial contributor. I get so lost and confused sometimes and the simplest things turn into the largest tasks to me. 

All of this has been causing me a lot of anger, depression, and anxiety. It always seems like it is something and whenever I take one step forward I take a hundred back. After three years of dealing with this my fiance is at the end of his patience. He is always trying to help and put things in front of me or ask me what he can do to help. and I in turn argue for no reason, become irritable, cause him stress, anger and resentment. It is really hard for me to have a conversation with him. I really do feel so much guilt for things I have done, pain I have caused, promises i have broken. I am so incredibly sorry and want to move forward. I just feel so hopeless and at a loss. I often times wish I could just take it all back and make it go away and magically fix myself. I wish I didnt dump everything on him. There are so many positive directions that this could go and I could turn it into. I just start thinking about it and get so overwhelmed that I cant figure out what to do. What the baby steps even are.