Cibil score dropped

So about a few months ago i opted for amazon pay later because i didnt have a cibil score prior to this.

i initially got a score of 729 but never utilised my pay later credit. So the score got maintained for like a few months.

It was last month I decided to finally use the pay later credit. Keep in mind the credit limit was just Rs. 2000 and i used about Rs. 1700. The bill came on 1st June and it got auto debited from my acc today, which was exactly on time. No late payment or anything like that.

But now my credit score dropped to 721. I looked it up on the net and the only possible reason i could find was that i utilised more than 30% of my available credit.

Would really appreciate it if someone could confirm that this is exactly the reason why. And if so what can i do to increase my score again?