You can have your boyfriend sponsor you for a fiancee visa, which is called a K1. it takes about a year to get it, give or take. Once you are granted the K1, you move to the US and you MUST get married within 90 days of your arrival. After you get married, you apply for adjustment of status, which depending on the USCIS closest to where you live, will depend how long that will take. Generally though you should have at least your work authorization within 3 months of sending in the AOS apps.
OR, you get married first, and your then husband petitions to sponsor you for a CR1 spouse visa, which also takes about a year to get, give or take. The CR1 is basically a green card, and allows you to work as soon as you arrive pretty much.
for info on marriage based immigration to the US see
http://www.visajourney.com
If you don't want to get married, then you'll have to find an employer to sponsor you for some sort of visa.