Go on thumbtack.com and put in your area code. Look for the 5 star ratings and read them. If I have any advice for you, it's to avoid speech level singing because it's just a bunch of crap you'll waste money on.

1. If you are too young to even sing in a church choir (and stuff)–then you are too young to be singing opera.
2. You HAVE to take voice lessons–and a lot of them–to sing classical music of any kind because of the difficulty of the music and learning the correct techniques so you don't damage your vocal cords trying to copy what you THINK an opera singer is doing.
3. You actually have to have a certain type of voice to sing opera (mainly naturally loud), but there is a wide variety of classical vocal music that even young singers and beginners can sing successfully—providing they do #2: take proper singing lessons.

There should be school choirs and children's choirs that you can try out for. This might give you a chance to sing some classical music unless all choirs have gone "Glee" on us. Some cities with local opera companies actually have age-appropriate opera productions and workshops for children interested in singing opera. Lot of these workshops are either very inexpensive or free, but many require auditions to participate. Usually they don't expect you to go in there singing an aria–a lot of these auditions will let you sing anything you want and even suggest things like "Happy Birthday".

Examples:
Http://www.seattleopera.org/discover/lea…
Http://www.laopera.com/community/Student…
Http://www.nycopera.com/education/
Http://www.opera-stl.org/education-commu…

Try searching online for "children's choruses" or "children's choirs" and the name of your city/county/state. You may find there is something locally that you can participate in.

Please don't mistake what you see on television talent shows as examples of opera singing. Very few of the singers on those shows would qualify as legit classical singers, and in the case of Paul Potts who won Britain's Got Talent one year, people were actually OUTRAGED when they discovered Mr. Potts did indeed have classical training and did sing in several full opera productions before he was on the show (an amateur, but they some folks thought that being less than "natural" was somehow "cheating").

Little girl singers are appealing, but most children have high sweet voices. Jackie Evancho, the current little girl "opera" diva is developing a very bad chin wobble–sign of bad technique and that she is seriously pushing her voice to sound as mature as possible. Her fans point out that she has the best of vocal coaches (because some people will teach anyone anything for the right price) and the best of throat doctors–which makes you wonder why she would need a team of throat doctors in the first place.

Don't mistake everything sung by sopranos or tenors as "opera". There are sopranos iand tenors in theatre music, folk music and pop. There are low-voiced singers in opera.

I think classical music is pretty too. That's why I sing it. But really, you can't sing this stuff without the proper technique or you won't be able to sing very long at all before your throat starts to hurt and your voice starts to give out.

Edit: I saw the added details mentioning you live in San Francisco. Your age still would be helpful. I presumed you might be in grade school or middle school since you said church choirs wouldn't take you unless you were an adult. Many church choirs at least accept older teenagers, but I guess it depends on the church and the choir. Some church choirs consist of paid professional singers so no amateur singer–no matter what age–would be able to "join".

Anyway here are some information about opera and classical music in your area:
Http://sfopera.com/Learn.aspx
Http://littleopera.org/
Https://www.sfcv.org/music-program/commu…
Https://www.sfcv.org/events-calendar/org…

You don't necessarily have to be gay to participate in the Youth Choirs:
Http://www.chanticleer.org/index.php/mus…

School will be starting soon. Try joining up then.

It depends on what you mean by horrible and how hard you are willing to work at it. My friends used to joke about my bad singing but I started practicing and taking voice lessons. I studied voice in college and I now sing in choirs and run a children's music program at my church. I really think if thats what you want to do then you should go after it! Just be prepared to practice practice practice. Also getting a book on music theory would help you a lot to.