Hello , welcome to the forum. Nice that you found the questionnaire right away
First of all: Brave to ask this here. Expect that the numbers and your life will be thrown at you hard.
No, it’s not that bad here. Sure, a lot will be commented on – I will do that too in a moment – but as long as you don’t dismiss all concerns, it will go smoothly. I mean, you already noticed that it could get tight, hence the questions here in the forum. Stay calm.
I have to ask a standard question: How much equity do you really have in total? Only the mentioned €25,000 or do you have more but want to contribute only €25,000? That is an important difference because every builder needs a five-figure cushion for unforeseen expenses. It will ALWAYS(!) get expensive.
Then you forgot how high your current savings rate is. Currently you have €800 warm rent. With a house you will have a monthly burden of maybe €1300 (the mentioned €1100 probably won’t be enough) + heating and other additional costs of at least €300. That’s €1600. Do you have this €800 difference unconditionally left over, without having to spend it on vacation, new cars, or anything else?