People say I look so young or small. Mostly both. I'm eighteen but I wear pants for an average fourteen year old. Some people say my face looks my age but some say I look like I'm in middle school. I feel like I'm not seen as equal to my peers because of my stature. (4'11.5" 95 lbs)
To answer your question; no this is not a bad thing. The idea of being "equal" is merely looking at this from a physical viewpoint. But many more factors appearance wise effect this too such as fashion sense and hairstyle. You sound like you expect people to judge you just by looking at you (without getting to know you). You mustn't let your mind get into this critical view of yourself because this can easily give birth to insecurities.
A lot of people like a girl that looks the way you do, it's called being petite and is desired by many men and envied by many women. A lot of girls hate being so tall that they can't wear heels or being broad enough they feel they look like a guy. Embrace being petite, it's a feminine factor you should be proud of.
Physical stature is not something that is really associated with status or prestige for women. For men a lack of it (especially height) can cause them to be discriminated against. I suppose if you look really young some people may not take you as seriously as they would if they knew you are a young adult and not a kid, so I assume that would be frustrating. But anyone you treats you in a patronizing way is only revealing their own immaturity.