Hey! I'm no expert but it seems that you should focus in cardio in order to have a lighter body and make your exercises easier.
Regarding the pull-ups, I've started 4 months ago and at first I couldn't do one single push up, so I chose to do assisted ones: put a chair below yourself and rest your legs there (not standing with your feet, but bending your knees), they were really useful in my case. I tried to do the jump negative pull-ups but they did not were comfortable to me.
I'm currently able to perform 5 or more normal pull-ups :) I would like to note that I'm doing parallel grip pull-ups as they are the easiest ones for me, I will re-try the other ones when I'm satisfied with these.
SimpleFit plan suggests that 3 assisted pull-ups are equal to a normal pull-up (for example, in Day 1 of Level 1 you should perform 3 assisted ones).
Never forget that you must be patient and persistent in order to see results.