Is it normal for a 10months baby to drink only 100ml every 3hrs? Is it too little? Solids will be 2-3 times and each time 2-3 table spoon.

As long as your baby is having enough wet/soiled diaper changed daily. This will be a good guideline to see if your baby is drinking enough. Different baby has different level of demand for milk/food. If your baby appear satisfied after each feed they should not be any reason for concern. However, if you are worried you can always visit a doctor to check if your baby is in the acceptable/healthy percentile