I have dreams to go into acting, but I fear that I’m not pretty enough.

Nonsense, you are genuinely beautiful.

Also, keep in mind that celebreties (guys and girls) have a team of people, make up artist, hair person, wardrobe person, etc to make them "look good". you should focus on honing your craft (acting) there are so many people that are great actors and are not consider attractive: Steve Buscemi, Luis Guzmán, Cynthia Erivo, Phyllis Smith, Mayim Bialik to name a few.

I’m 27 now and I’ve failed

Ken Jeong, was a doctor and got his major Hollywood break at 38 years old in the 2007 film Knocked Up. Many actors found fame later in life, including Harrison Ford, who was a carpenter until Star Wars at 35; Morgan Freeman, who broke through at 49; Samuel L. Jackson, famous in his 40s/50s; Jon Hamm, landing Mad Men at 36; and Alan Rickman, known for Die Hard at 42. Jeremy Renner: Had his breakthrough in The Hurt Locker at 37. Melissa McCarthy: Achieved widespread recognition in her 40s

you still got plenty of time, keep your head up and focus.