Thanks for query,
As You have a irregular periods
so it is difficult to judge from history only. At the same time you have negative pregnancy
test.You have get period on Saturday has no logic .You should wait for a week or two & then go again with proper pregnancy test as per directions mention on pack.
There were chances of being pregnancy as you have periods but i think you need to take hormonal
therapy to get it regular & then chances to conceive increases.