"I've been working with a trainer for two months. I really like her as a person and she definitely knows her stuff. I feel like she works me hard but I don't feel like she's pushing me as hard as she could. I'm getting results but not as quickly as I'd like to? How do I know if my trainer is pushing me hard enough? How do I know if my current trainer is going too easy on me? PS-If you use my question, please withhold my name and city because I know my trainer reads your column."
This is a really good question and it's something I check in with my clients on all the time. The person you really need to talk to about this is your trainer. You say that you are getting results, which is great. People base whether or not they are getting a good workout based on a set of benchmarks that aren't always the best indication. I've heard people measure a workout's value based on how much they sweat or cited a workout as being particularly good because they puked. Neither one of these things is proof that you've gotten in an especially good workout. There is an old bodybuilding concept of lifting to failure; to perform reps of a given exercise until you can no longer physically perform one more. Performing to failure is impractical for anyone that has to continue living life outside the gym once that workout is over.
You can't judge the effectiveness of a given workout based on any of these things. In fact, an individual workout can only really be judged in the context of a larger plan, because it is only through consistency that you will see results. Your fitness journey should be an ongoing and constantly evolving process. You workouts should be progressive in nature. Also, your workouts should enhance your life not prevent you from living your life outside the gym in discomfort. I can't tell you how many times I've heard people judge the merits of a workout based on their inability to lift their arms over their head or walk without pain the next day or how much they sweat.
I bring these things up because, while it is possible that your trainer could and possibly should be pushing you further in your sessions, it might also be possible that there is a method to her approach. I once had a male client in his early 20s start with me because he wanted to add muscle mass. After an initial physical assessment, I found that the muscles of his rotator cuff were underactive. I told him that before he could start benching all sorts of heavy weight on the bench press that we would have to develop those muscles. His form was also a mess. I told him we were going to drop the amount of weight we were using on almost everything so we could correct his form. In the long run, working like this would make it possible to achieve the long-term goal of putting on more size, and we could do so, while significantly reducing risk of injury. He worked with me for a few more weeks but became frustrated that we weren't using more weight. He ended up working with another trainer who was willing to "push him harder," and, unfortunately, he called me two months later to tell me that he tore his rotator cuff with his new trainer and that he wants to resume working with me again after he finishes physical therapy.
The best way to answer this question for yourself is to speak to your trainer. Tell her you're happy with the progress you have made but you feel like she can push you harder. She may be holding back for a valid reason and bringing the subject up may be a great way to open up communication about your goals, both in the long-term and the short-term. I assure you this won't be the first time someone has brought up a question like this and she is unlikely to be offended. Let me know how it goes.