I tried and tried to learn Guitar right-handed. I couldn't figure out why it was just NOT working. I could play piano, flute, bassoon, and many other instruments but I could NOT make guitar work.
I am STRONGLY left-handed. Then one day my husband came home with a left-handed banjo someone had given him and BINGO.. it just WORKED!
There are degrees of left-handedness. For those who are strongly left-handed, it can make a difference. I would suggest you see if you can get a chance to try a guitar strung for a left-hander.
When my daughter, who is also left-handed, started double bass, she first tried playing right-handed. Not only was it difficult for her, but she was still very young and she started to mix up the letters when she read. We quickly had her bass restrung to left-handed.
We ran into a lot of opposition.. she can never play in a symphony, etc. We figured if she went professional she could always play jazz or in chamber music etc. However, playing right-handed she would never reach her potential and be good enough to get INTO a symphony, let alone have those other choices.
Her playing improved dramatically when we made the switch to a left-handed strung bass. As it turned out she switched to harp later on so it wasn't an issue! Harp is actually more favorable to left-handers in how it's played.
During her bass playing years we talked to a lot of professional bass players. We discovered that most strongly left-handed players who were able to play well enough to make it professionally, were playing left-handed. There were a few who are left-handed and succeeded quiet well playing right handed. However when we talked in detail with them, most of those playing right-handed were not that strongly left-handed and some were close to ampidextrous.
There was a great old bass player at Disneyland. Some of you may have seen him. He used to play at the restraunt on the bayou there by Pirates of the Carribean. He played left-handed and we asked him once if he had ever gotten any grief for it. He said that he had studied for a time with Eugene Ormandy and that Ormandy had told him that he shouldn't play left-handed but that he did anyway.
Paul McCartney plays left-handed.
Don't give up, just have the guitar restrung left-handed and give it a try!!! Some guitars can be restrung with no accomidations, but for some you may just need to have the nut (the strip at the top of the fret board with grooves to hold the strings in place) replaced so that the string grooves match the gauge of the strings.
I'll admit this is a soapbox for me. If someone had just told me years earlier that I could just switch the stringing I wouldn't have lost those years of playing. Same with knitting. Yes SOME left-handers can do these right-handed, but many of us can't, or can't do them well that way and it gets old to be told we should be able to.
There is a reason the stringed instruments are played as they are. Because it's the MOST efficient way for the majority (right-handers) to play. However, if strongly left-handed, why handicap oneself when there is no need, and why feel less successful at an endevor than we have to?