I'm going to try to offer some suggestions since no one has had time to reply to you. Please know my comments are based on good experiences with other orchids but very limited (and not all that positive) experiences with Cymbidium.
As a rule of thumb, the medium is spent by the time you purchase any orchid. Not good to leave your orchid in decomposing medium. I'm told the best time to re-pot a Cymbidium is about right while it's still blooming or right after it's done blooming. The medium I used was from this US supplier-
I realize you are in Colombia and that it would cost a lot of money to order from over here but I'm thinking you might be able to find a local orchid nursery that provides some sort of a ready made Cymbidium medium for you to use? I didn't try growing enough Cymbidium to warrant me going out and purchasing ingredients to make my own mix so I was lazy and ordered pre-mixed. If you scroll down at their site you will find what they use in the mixes they sell for people growing Cymbidium so that should give you an idea of what would be an appropriate medium for your plant. There are professional growers who use a mix of peat, cypress, and perlite so that mix should be perfectly fine to use also.
Your plant is probably going to be root bound by the looks of all the growth and the blooms in your photo. Try rolling the pot on the floor while pushing down on the sides or squeezing the pot to help ease the plant out with less damage. Once it is out of the pot, try to work the old potting medium out of the roots with your fingers. Sometimes I hold orchids under the kitchen faucet to let water help me remove as much of the old medium from the roots as possible. Healthy roots should be white. If you find any that are black and mushy looking, cut them off. Continue to gently loosen the roots. Snip out the dead leaves while you've got the plant out of the pot and while you're at it, trim back the leaf that something chewed on that I see in the photo. Best to cut off that type of damage. Try to pick a pot that is only one size larger than what it was previously planted in. Over potting this type of plant can cause problems.
It's been too long for me to remember what fertilizer I used but I do know I used one on this plant while it was actively growing late winter into fall. I probably went online and looked up what people were suggesting and bought what ever seemed to be the most popular. I know that I tended to keep it well watered during that time but backed off on the water when its growth slowed down in fall. My girlfriend also uses a fertilizer but I have no idea which one she chose to use.
I managed to keep mine alive and very healthy looking but they never did bloom for me. What I learned is that they are a moderately high light plant. They love full morning sun but also need dappled afternoon sun. I had mine growing in an eastern exposure. I was able to provide them with full morning sun but no dappled afternoon sun. I should have used supplemental lighting but chose to give them away to a friend who had more appropriate lighting for the plants than what I could offer. I'm not too good about remembering to turn off and on supplemental lighting and I didn't want those particular orchids in with other orchids that were under lights on timers. I'm sort of out of space around my home for plants these days.
Now, my friend can't get them to bloom. They still look very healthy but they're not blooming for her either. We have just learned that the plants will not bloom unless there are nightly temperature drops into the 60's F for at least three months during summer. These plants like day time temps in the 80's with night time drops into the 60's but they can easily handle night time drops into the mid 50's. She was told that many people drop ice cubes on the plants at night before they go to bed to get them to bloom the next season. She has decided to give the plants away to another friend.
This is about all I know. They're supposedly an easy enough plant to grow and bloom providing all of their cultural requirements are met. I couldn't meet their lighting requirements without having to go to a lot of extra work which is why I gave them away. My friend offered them back to me and I laughed and told her "no way". I know darn well I would never remember to move them in front of an air conditioning vent during the summer and I know darn well I wouldn't remember to drop ice cubes on the top of their pots every night before I went to bed either.
I'm pretty good with other species of orchids but not the kind you have. Hopefully somebody who has better experiences than me comes along and comments to try to help you. Best wishes with your plant, it is really beautiful and it looks healthy.