Solid advice from virilep.
There's some degree of "you have it or you don't" with anything...from playing an instrument to being an endoscopist. The only person who will really make that determination, however, is you. If you have it in you to keep doing colons until you can get to the TI consistently, well then you will be a very good endoscopist
Nobody started out knowing how to perform these procedures...they all learned, just as you will. I'll add to virilep's advice: Be critical of yourself when you scope. I'm in my 9th month of fellowship...sure, I can spank the colon, slam the scope in and get to the cecum (which I think is the wrong way to do it), or I can be a little bit more careful, reduce around every turn (even if I fall back, so what, that means I have to keep practicing my reductions till I don't fall back), suction as I reduce, etc etc...and finish the procedure the RIGHT way, with a short scope, minimal looping, safe patient, and a half-decent look at the colon already.
Yes, it will take longer, and yes, other people will brag "I got to the cecum in August, blah blah blah." Who cares? The only person you need to be better than is yourself from yesterday. Don't be discouraged! Keep doing colons! Keep being critical of yourself in a constructive way! Listen to your attendings and watch their hands. It will all come together