my baby will not sleep!!!

My daughter is 11 weeks. She was doing pretty well with sleeping; she would go 6-7 hour stretches each night, which was awesome! She started going shorter and shorter stretches, and now she's eking up every 1.5-2 hours. She refuses to nap for more than 15-20 minutes during the day, and the only thing I can do to make her sleepy is nurse her! She outgrew her swaddle (we have a new one coming in today), so that probably hasn't helped. I'm going insane and I'm feeling physically terrible! We need sleep. Help!!