15-week old not sleeping...help!

My 15-week old has never been a “good sleeper” and her longest stretches at night have been 5-6 hours, and naps between 30mins and an hour during the day. She is exclusively breastfed and I feed her every 2-3 hours. I do drink two cups of coffee per day, I need it ha. So for the last week, things have gotten worse. She wakes up every 45 mins to an hour during the night. We’re lucky if we get a 1.5 hour stretch. We have a routine - bath and feeding - and usually try to get her down around 8-830. It’s gotten to the point where I sleep with her on my chest in the middle of the night (I’m so tired from lack of sleep I fall asleep while feeding her) Bc that’s the only place she’ll sleep for longer periods. But, I don’t want to get in a habit of that. Additionally, her hands and cheeks always seem so cold to the touch (esp at night) But I keep my heat on 73F - we live in MD - and it’s comfortably warm.

Anyway, is anyone else having this issue? Have advice? Am I doing something wrong? Thanks!