Need advice!

I want to be honest here. Im 17 and 6w and 4d pregnant. Me and my boyfriend have been together since May 19, 2011. I told my mom i was pregnant and she immediatly told me I needed an abortion and not to allow my boyfriend to have a say so in this, because having a kid will ruin my life. My boyfriend is 18 and has a job making roughly 300$ week. Im also graduating from highschool in may and starting college online in fall. How do I tell my mom I want to keep it? I feel like she only wants the one option for me. I cry everynight thinking about abortion....