Hey Sony,
Yes, after BSc Nutrition your skills are enough to become a nutritionist. You just have to complete a 6 months clinical setting experience as internship in a multi-speciality hospital and then have to earn a Registered Dietitian Nutritionists (RDNs) OR credential. But you should further do MSc Nutrition for  earning more knowledge in the field.
And you are also eligible to do MSC in Nutrition after BSc Biotechnology as per the eligibility of the course.
Good Luck!

Look, when you search for a nutritionist online, you see that it is considered by most people as a self proclaimed profession, which means, that there is no qualification required for terming yourself a nutritionist. Dietician on the other hand requires a proper qualification, and you can't really call yourself that without it. So I think you're referring to that. All the best!