It is important that you protect yourself, and get on the pill. Please do that right away. Thinking that you won't have sex, is foolish, and risky.
Even married couples who were completely prepared to have a baby, and had money in the bank to cover all the expenses, and good jobs to support a family, still have their lives turned upside down.
A baby is all consuming, demanding, unpredictable, and exhausting. Their needs take all your time and effort. Gone are long showers, and lazing around watching movies or going out with friends to party. You don't have time for anything, and everything revolves around that baby.
When the baby gets sick, get ready for even less sleep, and visits to the doctor, and following directions with medication.
Drop the teenage friends. Find your local library and join a new mothers group. Make friends with new mothers, who you share common interests and concerns. Learn what other new mothers are going through, and how to solve common problems. Sharing of information, good and bad (as it goes with a baby), is helpful to all.
Start reading more about babies and children, and child development. You will feel baffled at first because you are so young, but there is much you need to learn about as the baby grows and yes- becomes even more demanding. This isn't going to get easier, so you may as well be as prepared and educated as you can.
Get yourself back into school, and find a subsidy for the cost of having daycare for your baby. Get your diploma, and by that time, you should be ready to choose a career path, and then get on that road, and plan to graduate with a degree or diploma that will allow you to care for yourself- and your baby, without the support of anyone.
Drop the boyfriends and the companionship. You don't have time for it, and teenage boys don't make good fathers- a lesson you have already painfully learned.
Being a good mother isn't something that just happens. It takes work, and dedication, and very long hours of making sure the baby is well cared for in all regards. It isn't living in a flat with your sister who (God bless her generous heart) supports you. You need to plan to support yourself. Hanging around lamenting about lost friends is part of your past childhood. It no longer exists.
Get your priorities in order.