Welcome back to the forum, Lili.
You can still get pregnant even with a condom. The effectiveness of condoms at preventing pregnancy is only 98% under "normal" circumstances. That means a 2 out of 100 chance to get pregnant even when using one.
On top of this, I do not think brothel sex is "normal". The chances of someone trying to "stealth" (take the condom off when you're not looking) is much higher in a brothel, for example.