The forhead, chin, tip of the nose reference is for contraction strength. Sounds to me like you need to sit down with your preceptor and have her really explain these terms to you. While seasoned OB nurses use these terms willy nilly, it is kind of unfair to unleash them on new people without explaining what that means. I suggest first that you take a deep breath and understand that you are not alone. When I first did a vaginal exam, I was like...ummmmmmmm, what was that? It will take many exams before you really "get" what you are feeling and probably months, if not a year, before you feel comfortable. I have been doing them for 16 years and I still get an exam that stumps me.
Sometimes you have to dig around to find a cervix. My suggestion is always go into an exam thinking that you are going to find something and don't come out until you do (unless you are really hurting the patient). Think of the uterus being covered in a turtleneck sweater. The opening of the sweater is in the back of the uterus. As labor progresses, the opening (the neck of the sweater) is pulled forward, until it is in the opposite position in the front. So, in early stages, your exams will occur in the more posterior regions (and sometimes way behind there, and often times obliterated by a head) and other times it will be right there when you first go in. It will be different for every patient. The key is having patience. Sometimes you can feel the cervix but it is so far behind the uterus (the neck of the sweater is on the other side), that you really can't reach it totally. You can put your finger in the cervix and pull it towards you to bring it more anterior for you to examine. It does not always work, but it can be helpful when you are doing a very posterior exam. This is what your preceptor meant. A long cervix is actuallly referring to how much of your finger can go inside the cervix, the thickness. It is almost like sticking your finger in your mouth. Some cervix lengths go up to your first knuckle or even more depending on gestational age. Again, you will have to feel to get to know different effacements. If you put a piece of paper on the table and feel the difference between the table and the paper, that is 100%. My suggestion to you is examine as many people as you can. When I oriented, I examined everyone that came thru triage, even if I wasn't assigned there. The more you do it, the more familiar you will become. Remember, exams are very subjective. Your fingers may be a different size than someone else's, so your 3 may be someone else's 2 and so forth. It just takes practice and you have to give yourself that time. You do, however, need to ask your preceptor to teach you what she is talking about. She won't know you aren't getting it if you don't say anything. I wish you luck and I hope this helps you.