im a 34 year old black woman mother of two

im a 34 year old black woman mother of two.7 yr old son 9month old baby girl. while i have 2 kids they have different fathers my daughters dad has just the one and of course wants more although he claims my son as his own so while im still young and able i want to get it over with lol.. my menstrual is 3 days late im not sure what's going on i took 3 test all negative not sure what that means. with my daughter i was able to test 6 days early before the missed period.. its all very confusing.