Blood serum

Pa help naman mga mommy possible po ba na pregnant pag 10days delay and may discharge na brownish for 3days? Pero nag stop naman po regular po mensturation nag pt na po twice but negative po result. Pwede na po ba mag pa blood serum test? Malalaman poba agad kung buntis or hindi? By the way August8 pa po last mens. Sana po may makasagot thankyou in advance.