Zzzzz...so far I must admit that your attempt to 'help' me has been utterly disappointing, and I wonder r u really trying to help me or just repeating things people usually told when someone ask these kind of questions, are you even able to get the same effect as what I want or not cause so far all your 'helps' has been asking me to do things that I've already tried! And sorry me for whining but I need to get a rough idea where to start.
Grief, I told you exactly what you need to do, try reading
all the words in my post, particularly the ones in bold and if you had, you would have seen that is not what you were doing and my advice was basically the same as what Jessica said a couple of posts later.
And if you know your basics, working out the timing of when to do the shot is then possible.
You make your own 'luck'. I do not think Jessica's work has much to do with luck, a lot to do with practice and hard work maybe.
Though having said that - in the UK and with our very varied and unpredictable weather, Jessica would really struggle to get the shots of hers that you so like a lot of the time, so her being based in Southern California will help enormously.

There's a very good reason why the film industry set up in California - very consistent lighting/weather. The shot below was taken [in Sweden] in July and judging by current skies outside my window today, there's no chance of getting a shot like that as it's uniformly and resolutley grey, despite sunshine being forecast a couple of days back.
And yes I can do that sort of shot, as I know my photography basics inside out. This is the only one I could think of off hand - not a type of shot I do very often as most of my work is very different from Jessicas. And I live in the UK!
No filters, no PS. Just RAW file with some colour boosting and WB correction. Colours may be a bit off, just got two new monitors and not quite happy with calibration yet and sRGB stuff simply looks odd as it's a wide gamut display.
But this particular image was shot differently from Jessica's in several ways.
A wide angle zoom - more info below.
Another way of getting exposure more manageble with contre jour images is to use fill in flash. Though you can get a different sort of look that way. Looking at EXIF of the image above, Aperture Priorty + fill flash was used, but as camera has sun pointing directly into lens, you will only get a very teeny bit of fill light [in fact I only realised flash was even used by looking at EXIF] and AP was set to -1.67 and flash was probably set to underexpose as well. You can only use Auto setting well, if you know how to manually expose correctly IMHO.
Hmm, I guess this affect can only be achieved by a 1.2 or 1.4? How about 1.8 or 2.8?
The aperture only affects depth of field [if keeping exposure constant]. The shot above was taken at f4 on a 16-35mmF2.8 at 16mm but has a shallow DoF [for 16mm] as it's focused quite close. The different type of lens flare is due to a very different lens being used. F1.2 is only available on a couple of lenses 50mm+85mm and each focal length will influence how you shoot. But probably the most important thing when doing this sort of photography is your people skills and your compositional ability.