Depends on how dark you want it! If you want it be just tinted red then you don’t have to bleach but if you want it to actually look red indoors then yeah you’ll probably have to bleach to like a light brown/dark blonde.
As for your mom, I’m not really sure! :P First be like hey mom I’m pregnant. Then she’ll freak out and get really mad and then you’ll be like JK. And then be like aren’t you glad you have such a wonderful innocent child? And then ask her if you could do something to your hair and tell her you just want to dye it a little bit red. She’ll be so happy that you aren’t pregnant that she’ll be like YES <3
Or you could do something really great (like get a really nice report card or not cry at the dentist idk lol) and then be like mommy please let me dye my hair <3
Or you can ask her if she dyed her hair when she was young and then if she’s like yes act really interested and then you can be like wow cool can I do it!
LOL I dunno those are just a few things, but I bet you can find a crapload more on Google :P Hope this helps!