Lateral Canthoplasty in Asian Patient to Lengthen and Open Eyes?

Thank you for sharing your question and photo. Many young people have interest in lengthening their eyes horizontally. The problem is that the lid and skin are usually already tight and performing canthoplasty would make the eyelid tighter. This could cause several different problems. The other procedures you discussed are reasonable to have performed. 

Lateral canthoplasty will not be of much benefit for your tight lower lids. There is no sense in performing the procedure on someone who is very young and has very tight lower eyelid structure. It would only make your eyes smaller in vertical dimension. Lateral canthoplasty will not make your eyes bigger.

Lateral Canthoplasty is done the least after Double eyelid crease formation and medial epicanthoplasty.  The are good reasons for this.  The lateral canthal area is not the area that really defines the differences between an Asian and a Caucasian Eyelid.  The medial canthal area is the area where Asians mostly have a difference.  It is thought to be due to a lack of development of the nasal bridge or other arrested point. 
When you are developing all people have epicanthal folds.  These folds disappear as you develop in the womb.  In Asians, approximately 40-70%, have a persistent fold and they are called epicanthal folds.  The lateral canthi don't have major differences between the two groups.   Hence surgical correction of the medial epicanthal folds is where the most difference will be noticed.  That is also the reason why doing a lateral epicanthoplasty is a lot likely when one does Asian Blepharoplasty. 
Another reason that the lateral epicanthoplasties are not done is because they can readhere back to the orginal shape and the success rate is also a lot lower than compared with the medial epicanthoplasty. From your pictures, you have a wide enough horizontal dimension.  I think a double eyelid crease procedure and a little medial epicanthoplasty will really improve the appearance of your eyes.