Can you fix the shape of your eyes (go back to your old almond shape) once you have had eye lid surgery?

Surgery on the lower lids is tricky business. Once the architecture of the lid has been changed is very difficult to restore it. Nevertheless a canthoplasty Or some variation thereof can restore shape to the aperture in selected cases

There are many options available so without a personal consultation, it is hard to know precisely what you need. Photographs can be helpful to have a ball park idea of what might be needed.  You did not tell us when surgery was performed.  Be aware that persistent swelling which can last months will have an effect on eyelid shape.  So it is very helpful to let the eyelids heal.  For this reason we generally wait 6 to 12 months before performing revisional surgery.  In the mean time, yes for some an adverse outcome can be very depressing.  It can be very helpful to get professional psychological help for these feeling.  In some cases, antidepressants may be indicated.  Don't ignore your feelings, consider getting help if you need it.  For restorative eyelid surgery, you can't just go to any oculoplastic surgeon, you will need to find someone who focuses on this type of work to get the best result.

It would not be rare in a lower blepharoplasty, even if done well, to have some mild pulldown or drooping at the corners. This can change the angle and even show a little white of the eyes towards the outer corners. Your assumption is largely correct in that the angle can be changed by a 'tuck' of the corners although that tuck could be a tightening of the corner accompanied by either muscle resuspension or some form of canthal tendon adjustment. It is impossible to know which would be best without seeing some pictures.

The outside corners of the eyes (lateral canthi) can
be modified. It is not just a “small trick” adjustment. It is called a
lateral canthopexy, and involves surgically isolating the ligament under the
skin. It is then tightened, and moved upward if necessary.