Help I can't do pulls

So I workout at home and my back day was only with some dumbbells, then i brought a door pull bar and some rings.

I try some negatives at first with some scap pull ups and dead hangs, then try some youtube program from yellow guy where i had to do 2 pull ups x6 with rest time of 2-5 minutes.

I somehow manage to increase to 3x6 intil I realise that I CHEATED.

My pull up bar is too low and everytime i did a pull up i touched the floor with my feet realising all tension and when i try to do 1 with my legs bend i could manage only 1.

It seems the negatives suppose to be started with chest after the bar not chin so fuck those up as well.

I try to do some face pulls and australian pull ups after but is either I slip or don't know what position should I put the rings for any of those exercises pls help

And ya i have 100 kg dont tell me to loose weight I could not do 1 single push up and now I am doing 12-10 reps with 15 kg on my back so i can get stronger to lift that weight,

I just need some help with a program to increase my strength(core strenghting advices are welcome as well).