It may take a while, sometimes at an agonizingly slow pace it seems, for your vision to stabilize following dissipation of the gas bubble. Don't be overly concerned yet about residual blurriness, since mine took almost a year to settle into its final clarity following a vitrectomy/macular pucker surgery with gas bubble on my "good" eye. Also prior to this my own myopia got steadily worse, albeit slowly, until about age 50 when it seemed to stabilize. Be on the lookout for cataract development in your operative eye, it's a fairly common occurrence.
I can't address the RD issue, but to put the level of nearsightedness in perspective, your myopia is still in the range labeled "moderate myopia". Its only labeled high myopia when its -6 or worse. Although most people's nearsightedness stopped progressing by your age, some take longer. Even though you say your prescription gets worse each year, I'm suspecting since you are only at -5 by your age that the progression hasn't been that fast.
Even pre-made contact lenses go up to -10 for Air Optix Aqua, -12 for Acuvue Oaysys, and -20 for Proclear sphere, and custom contacts go beyond that.
The high blood pressure didn't cause the retinal detachment. RDs are caused by the vitreous tugging on the retina and tearing the retina which allows fluid to dissect under the retina and cause it to detach. HBP can damage the retina but not by causing RD. There is no way to stop progression of myopia other than in young children outdoor plan daily and reducing 'screen time". There is no way of predicting how near sighted you will be. Because you had a RD in one eye the chance of a RD in the other eye is very high one the order of 3-10%. Your retina surgeon can give you the best estimate based on what the back of your eye looks like. Hopefully your eye will make a good recovery, this is especially true if your RD was 'macula on" as opposed to 'macula off" Avoid contact sports and theme park type rides that jerk the head around and of course never go longer than a year without an ophthalmologist checking your eyes.