I think I wrote a post almost identical to this several months back, and I completely understand your frustration. I don't think it's reasonable to expect you to "get it" after only two SVEs. Someone once told me it takes about 100 exams to really "get it", and a lot more exams after that to get really good. Are you working with a preceptor? Do you have a dilation practice tool on your unit? If not, I purchased a pocket dilation guide that I keep in my pocket, and it is helpful, (although I never use it in front of a patient). http://www.pocketdilationguide.com/
When I first started and was working with my preceptors, I would "practice" on people who already had epidurals beacuse I wasn't feeling rushed or causing them any discomfort while I was trying to figure it out. My preceptor would go first and tell me what she assessed her dilation, effacement, and station to be. Then I would try, and then I understood better beacuse I knew what 2 centimeters felt like versus 5 centimeters, and what 50% feels like and what 100% feels like, etc. After doing that a few times then I would perform an SVE first and my preceptor would check behind me to verify. I've been in Labor & Delivery for less than a year and I still go through slumps where my exams aren't perfect or I just want someone to check behind me. Overall, I do feel better about my exams but there is definitely room for improvement.
But basically, I wouldn't panic over two exams yet.