Newborn baby eating too little, sleeping too much?

I need advice. Tomorrow my baby girl will be 3 weeks old. I constantly worry over her sleep and feeding routine. I've read and been told that they should feed every 2-4 hours and if they are sleeping, to wake them. Nights vary but last night she slept like a log waking only every 3 hours but nursed very weakly and for a very short time (5-8 min) only at one boob before she fell back asleep.this happened 3 times and finally at 9 I woke her up and again, she only took one boob for about 10 min. It took her 2 hours to fall back asleep (crying the whole time she was awake) I tried everything to soothe her and offered my boobs but she refused and got more angry. I even pumped some milk out and gave it to her from a bottle but she refused it. She also refuses pacis. I finally lay down with her on my side and she latched laying side ways. Not sure if this counts as a feeding since idk how much milk she got as a lot was on the blanket under her face.. anyway she fell asleep around 12? And it's 2pm now and idk if too much time has gone by without her eating. Is this behavior normal? Idk if I should call her doctor and have her get weighed again. She gained all her weight back plus some when we had the first doctors visit but I was supplementing with formula then. Now I feel she isn't putting on weight with just breastmilk (she is refusing formula) but my apt isn't till mid august