7 week old feeding every 1.5-2 hours

hi i'm a FTM to a 7 week old that I have been EBF. I feed her on demand per recommendation from everyone and every source I know. she currently has a rough schedule of eating every 1.5-2 hours for 15-20 minutes during the day and takes 1-2 feedings between 10pm-6am.

I am looking for advice on how I can elongate her daytime feeds a bit more? my hunch is that she's snacking and I want her to start doing full feeds. I wanted her to get into a schedule of eating every 3-4 hours during the day. I thought it was a poor latch situation so I offered her bottles of pumped milk (3-4oz) but she still got hungry within 2-2.5 hours. if I offer her more during the feed, she will sometimes take it but then spits up the milk and gets hungry again within 1.5-2 hours.

anyone else go through this? what can I do to elongate the time between her feeds? am I stuck with a snacker?

thanks for your help!