Are you insane????????? 5 ft 3in & 105lbs... your crusin' towards a serious health issue!
Just eat healthy & moderate workouts to keep toned.
Other than that you will look scary skinny, much like the walking dead skeletons wandering Hollywood & fashion magazines.
I'm always so scared for gals who are bombarded & believe in all the baloney the media feeds them/us about the "perfect" woman. Like looking "starved" is sexy. Just like too much weight is not attractive or healthy, too little weight is not attractive or healthy.
I'm 5ft 5in & 132lb solid muscle from running & weights ... I don't think I need to lose a lb. I'm healthy, trim & thin. I'm a curvy person & maybe some might think I need to lose a few lbs, but I think they are nuts!
Any less weight I'd start to have problems because the level of exercise I do requires a certain amount of food to keep up. In fact if I don't have a little snack before working out, I poop out before I'm finished. What's the point of working out if you lose energy halfway through?
My point is that we all have a "certain" point where we should be. It might not necessarily be the # you see on the scale. For every type of women there is, there is a healthy weight for each individual. & what works for me might not work for you or someone else. & what works for you won't work for me or someone else.
Just stay healthy & keep your weight where it is. If you want a change, start using weights.
Good luck to you & know that most women looking at your post think that "your at a perfect weight"!