hello and thanks for the query,
well given your history I would suggest you consult your gynaecologist immediately and get evaluated for pregnancy
as urine pregnancy test can be false negative also, what you are describing as feeling sick after eating could be what is described as morning sickness
and also the unusual spotting could not be normal so do get yourself evaluated thoroughly and please use protection henceforth if you want to avoid having such problems I m sure there will be some method of contraception
which you are comfortable with.