HI wai..! Women have different cycles. Those who are considered "regular" could have 21-days and some has 28-day cycle or even a bit longer. "Irregular" are just not predictable.
As you said that she ended her last period on march 1, as what everybody said...it is really too soon to tell.
If still in doubt, ask her to go to a laboratory to have her urine or blood taken for pregnancy test. For urine testing, most labs in the phils. would just do a normal pregnancy kit as what u get from the pharmacy. Testing in blood for beta-hcg (hormone that is produced in pregnancy) may be more accurate.
B-hcg normally is detectable (when pregnant) 3 wks from last menstruation then the concentration goes higher as the pregnancy progresses.
It is by the way the same hormone as what u detect in urine. She could have done it wrong or the kit could have been faulty.
If she still doesn't have her periods within next 2 weeks, then i suggest to go for any of these tests then ask for a copy of results after.

You do seem a nice guy who is being taken advantage by a professional scammer! Don't be a fool! Tell her to off!!!