"I am not sure if they will offer me the job." I'm not sure if a guy likes me. I'm not sure if he is interested in me. I'm not sure if I am pregnant. I'm not sure if I believe in God. I'm not sure if I can handle it. I'm not sure if I can make it. I'm not sure if I like her. I'm not sure if I like him. I'm not sure if I love him anymore. I'm not sure if I love him. I'm not sure if I should break up. I'm not sure if I should marry. I'm not sure if I understand your question.
So for this one you can write about I am not sure If I can do that as the easiest one. Behind sure if you need to talk about I can, or if this is what. You need some words to make the clear explanation very well here. Here this is quite important to use if or that to make the transition words and there are many examples I can show you. For example I am not sure if this is working well or I am not sure if you are right, really simple, don't need to care much more for this grammar problems. I am not sure that is correct, here you are using that to point out a thing, but you can also use that as a transition word for example I am not sure that this can work, so you are using the transition word there to make the representation of stop as an important point of greeting in English. Not much things to be careful with grammar. Go ahead to try some, don't make a sentence to long in English is the best.
if it's going to.. if that is working, or not sure that if this is--this one is also okay, but if you somehow think that it's sound with some extra words, then don't put if behind, just say not sure that this is.. or just straight ahead with not sure if... Hope this help, just try some by yourself, this one is very easy