So many times I got hit by this kind of thing during my entire FFXI career. Shiia is actually my 3rd character. First one was an elvaan. Well not even knowing left and right and have been chosen to start as a blm starting in bastok (hey... in EQ the high elves were almost best spell casters -_-

. Then I noticed I haven't been doing well. I mean, I never saw a muscle type elvaan who are good melees instead of mages.
So I swapped to elvaan starting in windrust. Well eehh... thought the nation changed your stats. Again I failed being a good mage of lack of mp around lvl 15ish. That was 3 month after I started playing. Shiia was born next. Having told humes were good in all jobs but not being the best, I wanted to try everything and every job which is why I chose a hume for my 3rd character.
I played around as war for a bit. I hit 11 solo, with couple of small groups in between. My serious grouping was around 12. I was the tank in the group. I knew already about the macro use, provoking every 30sec stuff. But soon after hit 15, I saw the huge lack of whms. So I decided to turn into a whm.
My next target was pld. So I quickly became lvl 30 as whm and swapped to pld. I played alot and reached 27. This is the time when I noticed I cannot solo jack past certain point in this game. They simply hit too hard, and I hit too low. After meeting with 2 friend of mine who are currently in my ls, told me rdm were good in getting group, and able to solo smooth. So yet again, I swapped. I hopped till 70 pretty quick, it was around lvl 50ish when my best friend Punitan started to play. After 9 defeats with maat (8 pre patch), I just got sick of rdm. Party invites were constant yet I was unable to get through genkai5. So I swapped to mnk for a change. A melee dedicated job. It was a big change. And I saw many fellow rdms during the course, and noted down what they did good, what they did bad etc. Soon after I hit 68, Punitan was already reaching the high 60s. So I though what the hell, I will try beating that old bastard for once. And I beat him after the patch (BIG CHANGE). My monk and rdm both hitted 72 and 74, punitan started leveling summoner after he aquired fenrir (as 71 whm).
After a while of thinking what would be fun for me, I still had my Wizard memories back in EQ. The ultimate elemental user, and big boom user. So I ended up leveling my rusted blm who was on hold at 37. Ever since it was my first job to level till 75.
Long story short, trying alot of jobs is interesting, and fun. Also you will comprehend more about your current, last, future jobs while observing the performance of the others wether they are good or bad. I am now working for 75 on both rdm and monk once I get my funds again. Punitan is now working for brd after he achieved his lvl 70 goal as a summoner. But probably will continue summoner whm and bard till 75.
If you were a melee job, try a mage job. If not try something which was different from your current role like a tank, healer, nuker, supporter for a change. You might see the light in some questions you had before.