You have completed 35th day of amenorrhoea with pregnancy
test negative on 31st.
Basically home pregnancy test is done immediately after missed period or after 7 days from missed to get good result.
You should have to repeat the test with pregakit along with a blood test
for confirmation of pregnancy.
Missed or delayed period has several reasons other than pregnancy like emotional upset, stress, thyroid
problem, PCOD, anorexia
......so need to investigate properly.
Consult with your gynaecologist if period delaying more than 2 months with exclusion of pregnancy.
For more suggestion,mail me....my id:firstname.lastname@example.org
All the best.