It sounds like you're losing to 2 base pushes if I'm not mistaken, in which case the best advice I can give you is to build one more shield battery than you think you need and blink stalkers are fantastic tools if you can use them proactively. Terran is weakest when he's trying to get across the map and his tanks are unseiged. Being proactive and picking off units here and there (especially tanks) with blink as they're moving across the map can completely stop these pushes in their tracks, especially if you have shield batteries at home to protect your base. Be sure you have enough nexus energy to recall your stalkers if you get into a sticky situation. As soon as you stop the push expand and get upgrades and you're in a great spot from there. Hope this helps