Consider why your bedroom is so bad, particularly as you already have boosters
Could it be the type of brickwork and a particularly solid area, or part of the property has had an extension with former external walls inside or two properties knocked into one etc
It could also be interference from other electricals or a combination
You can try repositioning the existing boosters to see if they can make a better ‘path’
eg instead of placing boosters midway, place them in a direction - such as aligning with doorways
An alternative to ‘standard’ boosters which repeat the signal is a wired network (no need to install network cables these days, but to use a powerline system which runs through the electrical system
(note that if there are multiple sets of wiring in a building then this may not work - eg if it had been an extension / knock through)
Look up ‘powerline adaptors’ - the price range can vary.
Where possible use an Ethernet cable into the powerline adaptor - eg at your virgin router plug in one adaptor to the mains and a cable from the router to the adaptor
Then in the bedroom just plug in a wifi powerline adaptor (or in the hall if it works to get the wider benefit upstairs)
…….
A non hardware solution is to experiment with wifi frequencies, your router should have multiple options and can probably run more than one at a time
For example 2.4ghz and 5ghz
5ghz is generally the ‘better’ for higher speed etc, but is a weaker signal with less range
2.4ghz is slower, but with a longer range
Check your router settings and switch on the dual band option, that would give you two networks to connect to. Try each of them in different rooms - and possibly combine dual bands with the routing of extenders to compare results