Am I pregnant....are these symptoms?

Me and my husband are TTC and we had about a week ago. About 3 or 4 days ago there was some brown spots in my undies and some light brown discharge when I whip (sorry TMI). I have also been having pains in my lower and sometimes my upper stomach. I took a HPT last night but it was negative. Also my periods are not regular right now since I just had a baby two months ago but he didn't live long. Please help me...could I be pregnant? Thank you and God Bless.