Yes buddy, you're supposed to get 6-7 hours of sleep but you're supposed to get them during the night. There's a thing called circadian rhythm which should regulate your daily activities. Sleeping during the day may cause insomnia which can cause hallucinations or messed up vision.
Also, it's true that schizophrenics sometimes report fake paranormal events , however , you should know that there are a ton of stuff which can make a normal person see/hear things.
Considering that this has happened to your for all your life , it's probably not caused by a single reason ( like insomnia ) but rather by several small disturbances clocked together.
Don't get me wrong , I'm not trying to bash on you and your girlfriend (considering that you say that she's seen what you saw as well) ; it's just that I'm a skeptic and so I'm just doing my skeptic homework here. I can't just jump into giving paranormal advices since I'm a non-believer myself.
But if it seriously disturbs your personal life , you should , by all means , find other ways to get opinions. See several psychiatrists , see several priests , ask on other forums , try Yahoo Answers , talk to your family and friends.
As for the part regarding the difference between what is real and what isn't : you never know. Schizophrenics really believe what they see. Don't get me wrong. I'm not saying you're a schizophrenic , I'm just implying that you can never know one thing for certain if you only view it through your perspective.
I hope you'll manage to solve your problem