Hi,
Welcome to icliniq.com.
Let me start by assuring you that your baby is absolutely fine and will not have any problems in future life. Let me tell you how. Usually, mother always has a poor appetite and poor food intake during the first half of pregnancy. This is due to the hormones of pregnancy. Your weight may even decrease during this period. But God has bestowed baby with the quality that it will absorb all the required nutrients from the mother's body. So mother loses all the nutrients, if she takes food during this time, then she will feel better, baby is always fine. During the second half of pregnancy, especially after 28 weeks baby starts growing very fast and needs lots of nutrition. Your weight should have started during this time. To give you a rough idea- baby weight near 32 weeks is around 3.8 lbs and in just next 8 weeks, that is at 40 weeks it will weigh more than 7 lbs. So you are very well within the normal range.
Ketone bodies are usually negative and indicates your hydration. If you do not take enough amount of water, this will increase. To affect baby brain, the level should be very very high and stay so for many days. When you say that your weight has increased, then there is nothing to worry. To allay your concerns; just have a scan. Take 2 scans at 4 weeks interval. If they show adequate sequential growth, it means baby has got adequate blood supply, nutrients and you have nothing to worry. I would like you to concentrate what you have in hand. You have 8 weeks to go. Just keep eating whatever you like, lots of sweets (if diabetes in pregnancy has been ruled out), high protein diet, plenty of fluids. This will keep you hydrated and also supply sufficient nutrients to baby. Rest assured baby will be fine and with normal brain growth. All you need to further think of is to have nutritious food now on.