For all scared girls out there

Right now I'm going through something probably a lot of you have/ are going through. I don't know whether I'm pregnant or not. No this isn't one of those "we didn't use a condom and he came inside of me could I pregnant??" This is a "we used a condom we was safe". However, things go wrong. I'm prone to panic attacks so that's all I've been having for the last few weeks. 
My periods are and have never been on time for the past 6 years so I didn't know what this was. 
I'm very lost and scared at this moment and I'm getting a pregnancy test on Monday and preparing myself for the worst. I'm 17 I don't want a child right now when I know I could not give it the life it deserves. This why I respect all mothers out there so much. 
I know a lot of people going through this would love some advice and so would I, so please I beg of you. Please give us some. I will update you on what happens. 
Thank you so much.