Hey, if I put down on my taxes that I can be "claimed as a dependent" but I haven't been claimed, and couldn't because my mom doesnt work am I still a dependent?

you are a dependent if you meet certain conditions even if you are not claimed. the tests are.

Qualifying child
1) Related
2) Same principal abode as taxpayer for more than ½ the tax year. Temporary absences like for school are ignored
3) If not a full-time student, under 19 at the end of the tax year. If a full-time student under 24 at end of tax year.
Full -time means an individual who during each of 5 calendar months during the calendar year in which the taxable year of the taxpayer begins is a full-time student at an educational organization described in section 170(b)(1)(A)(ii), or is pursuing a full-time course of institutional on-farm training under the supervision of an accredited agent of an educational organization described in or of a State or political subdivision of a State.
4) Hasn’t provided over ½ his/her own support

of you provide over 1/2 your support, you can't be claimed as a qualifying child

the we have to see if you meet the qualifying relative tests

Qualifying Relative

• meets relationship test - this test is met  
• your gross income for 2019 is less than $4,200
• you didn't provide over ½ your support
• isn’t a qualifying child of another taxpayer

if you are not a qualifying relative either then no one can claim you as a dependent

so you would not check the box that you can be claimed.

you teacher shouldn't be giving tax advice

but I doubt you'll get anything from the stimulus since it's based on 2018 returns.