Eye twitch for 6+ months

I’ve had an eye twitch on my right top eyelid for over 6 months now. I can’t figure out why it won’t go away.

• I’ve given up caffeine about 5 months ago
• I get plenty of sleep (9-10hrs/night)
• I drink 2l water per day
• I don’t feel particularly stressed (I do have anxiety but went on meds about 3 months ago and it has improved)
• I got a blood test about 4 months ago and wasn’t deficient in anything
• I went to the optometrist 2 months ago and they said all looked fine
• My eyes don’t feel dry
• I do spend a lot of time on the computer as I am a graphic designer

Any ideas what else it could be? It even twitches when I am in bed at night with my eyes closed.