It could have been worse. Getting a single point from Portugal would be a major achievement, and I'm wary of any attempt to downplay them. Serbia I'm happy with, that's a team I think we could be capable of getting more points against than we'd lose, if we can play to the level we are capable of. Luxembourg, I'm wary of. They've had good results recently, and only lost 2-0 to Portugal last year (the second was in the last minute), and Serbia 3-2. I'm sure their coaching team will be explicitly telling them to target the Ireland games for scalps. Azerbaijan, the away trip is a ballache, but they shipped 18 goals in the last qualifying campaign and only won a point, so anything other than two wins is a disaster.
I think third is the most likely possibility, but second is far from unobtainable.