IRREGULAR AND TTC

So on December 1st 2017 I had a regular 7 days period but my period disappeared until July 15th-23rd . And I’ve been trying to conceive every since the day after my period ended . I’m just looking for help and advice . When do you think I should take a pregnancy test ? Do you think I’ll get a positive result ? What are some health tricks I need to know ? By the way I’m a mother of 1 already but he is about to become 4 next month . Also this is a picture of my old period app because it has 2 years of my data in it .