Welcome back, Coqui. My best advice to you is to seek out the counselors at a family planning clinic such as Planned Parenthood. You can find one near you here on their website. Just enter your zipcode.
Planned Parenthood
Don't worry about money. They operate on a sliding scale based on need and ability to pay. They can give you a pregnancy test and answer all your other questions. If you prefer to do a home test, they will advise you on which brand is the most reliable.
Planned Parenthood is where I went to for my birth control needs as a young woman short on finances many years ago. They are an amazing wealth of information on woman's health, family planning and sex education.
Best of all, most of their staff are people who have "been there" and understand what you're going through and know what questions you need to ask and have answered.
Here's another page on the Planned Parenthood website that deals with Teen issues and the questions teens have.
http://www.plannedparenthood.org/teens/