Pregnant while feeding?

I have a 3 month old baby and am feeding. My husband had a vasectomy right after the birth of this baby and I got a depo vera shot. There is a 3 month waiting time for a vasectomy to be "final" and a week waiting for depo to work. I have had one period which seems forever ago and I do not remember when it is. I took a pregnancy test but walked away and forgot to read the results until later. When I did read it there was a second line but very faint. I know you are not pyscic and do not know if I am pregnant, but has anyone been pregnant when the line was very faint? I am freaking out and do not have the money to take another test. I already have three kids. Any answers would be helpful! Thank you!