The term "fussy eater", for diagnostic reasons, can really only be applied to children over 6 years of age. Until this stage in development the child is still learning about foods and textures. This does not mean that concerns, arising from eating behaviour before this, are invalid.
Children who have had reflux or colic lasting most of their infancy are not going to find the process of eating and being satisfied, at all comforting and may refuse foods for that reason.
Mealtimes can be the one time the child feels that they can have any control over their day and for that reason may take all the control that they can.
In general, no child will starve themselves. If you are concerned about your child's eating pattern then making a note of what and how much food they eat over a two week period is much more helpful than looking at amounts taken over a day. Children's appettites change over a day and over a week dependant on growth spurts, levels of activity, feelings of "wellness" and other factors. You may find that they do take in enough food over this period and are growing and gaining in height and weight although your initial perception was that your child wasn't a good eater.
If you have concerns about your child's eating habits it may be worthwhile having a proper feeding assessment done. This will give you a better idea of how to cope and, if another professional could be of assistance.
Dream-Angus.com offers exactly this service. Call for a free, no obligation consultation and then decide if you will take this further.