You may have since had success with this, so here's some tips to keep in mind for future sexual encounters. Saliva dries quickly so it's ineffective as a lubricant. A dry entry is going to be more challenging for you, as well as being uncomfortable for her. Even if she orgasms during foreplay, she will only be wet on the inside. Think of lube as being the bridge between the inside and outside. Stay away from chemical lubes as they burn. Search organic personal lubricant online.
If she's in her head having random thoughts or worrying, then her body will become tense. Get her to focus her attention on you, and how much she loves being close to you. This will switch her attention from thoughts to feeling, which will help remove tension to allow for a more comfortable entry - and naturally make her more orgasmic.