Hey,
I'm 15 too,and I'm 19 weeks pregnant.I only found out last week though.It's good that you have your boyfriend's support,so you aren't completely on your own.It's going to be hard for your parents-it was for mine-but now,they're just as excited as me.If you don't have a close relationship with your parents don't worry-this could bring you all closer.It did for my family.If you want to keep the baby,just think-they may glare at you for a while,but once they actually see their grandchild,they'll fall in love.
But seriously,talk to them.Show them how much you need them,and talk over every option with them.You don't need to quit school-I'm continuing with my exams this year,and I'm going back to school for A levels,and I'm planning on going to uni.A baby doesn;t necessarily need to ruin your life-your plans may be a little harder,and take a little longer to accomplish.
As for being a slut-well,of course your not! Accidents happen to the very best of us.I've been with my boyfriend 2 years.We lost it to each other-that hardly makes me a slut,though I'm going to be a teen mum.
Being pregnant and having a child means you will be feeling things that your friends haven't experienced and can;t imagine.Ignore them:they don't understand.True friends will stand by you:those who won't aren't worth your time.What matters is your health and happiness.
And don't forget:they may call you names today,but tomorrow it could be them.Hope all goes well for you.