Nacho,
Sounds like you're making good progress on the stretching. It looks like both of us are pretty much along the same stage in SFQ and stretching.
I've been doing stretching for a few months now and the best I've been able to do so far is get into half lotus for 30-60 minutes at a time. I feel I could just about force myself to go into full lotus but this would be forcing it and cause real pain so I've developed a system that's getting me there with relative ease: Once in the half lotus I simply get hold of one knee at a time and move it up and down (without unfolding the leg), moving as close to my torso as possible and then back flat onto the ground. I alternate both knees and also alternate which leg goes on top. Do this for 2-5 minutes and then relax leg back into half lotus, continue watching TV etc or doing small universe. Then after another 15 minutes do the knee raises again. You can intersperse a small walk to the end of the room and back in between also. I find the second and subsequent times I do the knee raises I can stretch further and on a good day I come close to locking my legs but I'm not going that far yet and will probably give these exercises another 3 or 4 months at least before I attempt that. Unfortunately I've not found the recommended exercises on the video to be of much help - but that could be just me.
Another good tip would be to try full lotus in a sauna if that's possible. In such conditions your muscles and ligaments really loosen up and expand given them the extra leverage needed. Again I recommend the knee moves. Failing that try sit out on a sunny day to practice these stretches. Thos living in Florida will find this a breeze as it's a virtual open air sauna
Here in the UK we're experiencing a heat wave and the temperature has definitely helped me. Muscles and limbs are much more supple.
It is also important to realise that ones diet can affect as much if not more than the outside conditions. Certain foods that fit into the "cold" category generally tend to act in a way similar to if you were out in the cold. And of course other foods can have the effect of doing the reverse... without going into a detailed list of foods I suggest you eat a healthy balance of food items and refrain from too many cold, fizzy drinks in particular, eat plenty of beans, eggs, milk, fish and chicken.
Respect
Hakim