wishes for a 3rd

As far as I know, your GP doesn't prescribe hormone treatments, but they can do (preliminary) tests.
But first, look at the most obvious (and easiest to fix) cause: not enough sex during your fertile window. A family with 2 kids is busy, and maybe you're often too tired or too busy with other things to have sex often. And as a woman, you're only fertile for a short time each cycle, so you could easily miss it if you don't have sex for a week or so.

One way to 'hit the mark' is to pay attention to the mucus coming from your vagina. This mucus is produced by your cervix and varies throughout the cycle. The more abundant and fluid it is, the more fertile you are. If you have sex during the time when you produce a lot and/or stretchy mucus, you have the highest chance of getting pregnant (having sex once every 1-2 days is sufficient). For most women, this period is from about 10 days to about 15 days after their period. But check how it is for you, because it depends on how long and regular your cycle is. The longer your cycle lasts, the later your ovulation (and thus your 'fertile' mucus) occurs.

Thanks Edith for your reply. Yes, that's also a reason that plays a role. You have little time, are busy, and I apparently miss my fertile days. So I'll try again to time it during my fertile period, and if it still doesn't work, then I'll see a doctor. Because I got pregnant quickly with my two princesses too. So it should basically work now too. Thanks also for the tips. Greetings, Madelene