What is my canthal tilt? Trying to figure out if canthoplasty is in my future (Photo)

Your canthal tilt is normal. You don't need a lateral canthoplasty.
You have mild lower lid retraction (your lower eyelid is slightly rounded on the outside edge). It can be improved using a small graft on the inside of your lower eyelid. This will make it seem like you have positive tilt.
You do also have a slight upper eyelid ptosis on the left (droopy eyelid).
I would recommend you see an Oculofacial Plastic Surgeon (Oculoplastics) for these issues, which are admittedly subtle.

Eye shape is determined by multiple factors including eyeballs, eyelids, and bony orbits. You are likely referring to relative lower eyelid retraction (droopy lower eyelids) which can be elevated but need more detailed evaluation. See an expert.

In most individuals, the canthal tilt is neutral or positive. Neutral means that the inner and outer canthal angles are about level. Positive means that the outer canthal angle is higher that the inner canthus. Negative means that the outer canthal angle is lower than the inner canthus. We like a neutral or positive canthal angle. Yours are neutral. The surgery that raises the corner is called lateral canthoplasty. The surgery called canthopexy is not strong enough to permanently change the outer angle. Now before you run out and ask for this surgery, please understand that is generally not a cosmetic procedure but a reconstructive method. Over correcting the corner can look highly unnatural. Often surgeons who do this, destroy some of the lower eyelid. That makes fixing their work and restoring the shape of the eye challenging. Please be careful what you look for. Your eyes are beautiful but you appear to have a mild left upper eyelid ptosis. That is addressed with ptosis surgery not canthal surgery.