Lots of sports and still gaining a lot of weight.

Could it be that you started out underweight?

I'm 1.68m and weighed 54, now I'm 62kg. I had a BMI of 19, so no underweight.

Recommended weight gain based on BMI at the very beginning of pregnancy (calculate your BMI here):

12.5 – 18 kg if BMI is higher than 18.5 (underweight)
11.5 – 16 kg if BMI is between 18.5 – 25 (normal weight)
7 – 11.5 kg if BMI is 25 – 30 (overweight)
5 – 9 kg if BMI is higher than 30 (obesity)

As you can see from this overview, it’s not weird at all that you’ve gained this much weight right now. With your starting weight, that’s perfectly fine. Your baby needs to grow, and your body needs to prepare to make that possible.

Share your feelings with your midwife! Because reading between the lines, I get the impression that you’re already obsessively exercising to keep your weight down. If that’s really the case, it could be bad for your baby. This list above is just a guideline and won’t apply to everyone. But do have that conversation with your midwife.

I lost 30 kg before my pregnancy, ran 8 km three times a week.
2 little ones at home and walk the dog for 30 min every day.
Between 1000 and 1200 calories per day, low carbs.
Now 18 weeks pregnant, gained 8 kg.
Lots of fluids, that's why I wear compression stockings. In warm weather I'm bloated, gaining about 1 kg per day, but still.
Now I do fitness twice a week
and still gain weight.
It's normal.
With my previous 2 pregnancies I also gained a lot.
After 9 months I was even a bit lighter than before my pregnancy.
It's not different. From January I'll start exercising again and eat drastically less.
If I do that now I'll be nauseous.