Hi fitpharma. The protein powder I prefer (PlantFusion Vanilla Bean) contains sweeteners, so that won't work for you. I just wanted to caution that as you look for protein powders, be aware that many popular mainstream protein powders have tested positive for heavy metal (lead) contamination in a recent study. Google it and you will be able to see which brands are safe and which are not.
Honestly, while I do still use protein powder, the contamination issue has really made me rethink my reliance on protein powder. My first baby was IUGR so I had to eat LOTS of protein later in my pregnancy, and I found that it was actually pretty easy to do using real foods. I would eat lots of eggs, greek yogurt, and be creative with my meals, like a grilled chicken salad for breakfast (sounds gross but it was yummy!). There are also often overlooked foods like quinoa, sprouted grains, lentils, beans, nuts, and seeds that can really boost your protein consumption.
Best wishes for a healthy pregnancy!