We started off being 3 hours between feeds, last week that went down to 1 hour between feeds, particularly from noonish onwards.
Welcome to the 2nd week growth spurt!! That sounds very normal to me. You don't mention anything about growth spurts so did you know to expect something like this?
The link recommended above talks a bit about growth spurts. They can last up to a week so it could still be happening now.
Is mixed feeding something you'd planned on doing or would you like to return to exclusive breastfeeding? You might want to bear in mind that in these early days if you do supplement it could have quite an effect on your supply so if you do want to continue breastfeeding - even if it's mixed feeding - you may want to about getting help to increase your supply. You may have missed the opportunity of developing your milk supply during this growth spurt by supplementing.
I would really really recommend you talk to someone trained if you would like to breastfeed long-term. Mixed feeding is successful for lots of people but some people have supply problems (especially if they start this early) and end up phasing breastfeeding out entirely.
If you are in the UK there are lots of helplines which are free.
Check out this link:
https://babywhispererforums.com/index.php?topic=63627.0They can talk to you about supply issues and give you loads of advice. If you don't gel with the first person you talk to then phone someone else.
Finally do know that some people take a little while before they start EASY. The first few weeks are an important time to get your milk supply established. Do ring someone if you would like some qualified breastfeeding advice.
Sorry if I sound pushy!