Those look like beautiful plants. They are just different genetic traits expressing since they are different strains. Whats really crazy is that you can pop one pack of seeds all the same strain and get various looking plants. Its whats called a phenotype; the way a plants genetics express based on the environment its grown in.
Your plants have tons of growing left to do and might totally surprise you with how they change. Don't put any thought into the number of weeks flowering or when to harvest them. Just focus on keeping them healthy and letting them grow to their full potential.
More nutrients DO NOT make bigger buds.
If you keep us updated later on in the plants lives we can help you figure out when they start to show signs of maturity, or if there are signs of problems along the way.