pregnant and stretch marks

Just eat healthy and take folic acid from now on. You can't change the fact that you followed a diet before, but it probably won't do much harm since you've stopped now. Just enjoy eating healthy and start enjoying your pregnancy!!

Definitely start eating healthy from now on. You can't change anything about it, so don't feel guilty.
Maybe you could contact a dietitian. Not to lose weight, but to help you with healthy eating, and she might help you during your pregnancy. What's too much or too little, etc.

First of all: congratulations on your pregnancy!
And as Elsie and other Anoniem also say: you don’t need to feel guilty, and from now on you can just start eating enough and healthily again. An unborn baby is like a little parasite: it takes from mom what it needs Especially since it’s still so small, you don’t need to worry that it’s missed out on anything. It would only become an issue if you were on a very strict and long-term diet during pregnancy (comparable to a famine for your body), but luckily that’s not the case in your situation.

Just keep in mind that you’ll probably start gaining weight quite quickly in the coming weeks. You’ve been dieting strictly and lost quite a few kilos in a short time, which unfortunately always carries the risk of the yo-yo effect. And of course, you’ll also gain weight due to the pregnancy itself. So all of this together might come as quite a shock. Resist the urge to start dieting again; definitely discuss any concerns about your weight with your midwife/gynecologist.
Good luck!