I know you are probably REALLY tired at this point and are anxious about returning to work, so I am sure this is very frustrating. At her age, however, it may still be hard for her to have a set routine. She should be getting at least three naps a day and giving you longer stretches at night....do you have a routine before bed so she knows it is night time? How long do you let her struggle before you go in to hold her? Is she swaddled? All three of my kids started sleeping longer stretches around three months, but they were four months old before they really slept. I recommend you choose a sleep strategy that works for you and your life style and try it for several weeks. I highly recommend Healthy Sleep Habits, Happy Child....the premise is sleep begets sleep, the more opportunity you give you child to sleep the longer and better they will sleep. soothing routines are recommended (swaddling, bath, sucking (bottle, pacifier, nursing).
As for teething, while none of mine cut teeth before 11 months old, teething signs started as early as two months (drooling, etc).