I think you need some more tools. Instead of doing Spread Strangles, look at the Iron Condor trades on the news plan. Iron Condors are for ranging markets or for a move and then a pull back which can often happen with news.
For spreads check out this webinar Darrell did. This is for slow moving markets no news required.
if you are not an Elite paying member, you may want to consider doing a 30 day trial, learn the Power Plays in addition to the above and take your trading to the next level with Nadex.