There are a few classes you can multiclass into to gain skills, such as Bard, Ranger or Rogue.
In addition to that, in the player's handbook there is a feat called "Skilled" which allows you to gain proficiency in any combination of 3 skills or tools.
In Xanathar's Guide to Everything, we have the Prodigy feat which gives a skill proficiency and a few other things, but can only be taken by a Human, Half-Orc, or Half-Elf.
In Tasha's Cauldron of Everything, the feat Skill Expert gives proficiency in a skill and a few other benefits, with no racial prerequisite.
There is also a bard ability in the college of lore that allows you to learn 3 more skills at level 3.
Currently, the downtime rules allow you to gain proficiency in tools but not skills.
In case it isn't clear, you don't have to pick skills from your class skill list when you gain new skills through the "Skilled" feat. You can pick any skill you want.
You seem to have the correct amount. Here is a breakdown of why:
When starting off at level 1 as a Rogue you get to choose four from Acrobatics, Athletics, Deception, Insight, Intimidation, Investigation, Perception, Performance, Persuasion, Sleight of Hand, and Stealth, plus proficiency in Thieves' tools.
So far we're at four, plus one in tools.
Criminal background gives you proficiency in Deception, Stealth, a gaming set, and thieves' tools. When you get proficiency in a tool that you already have proficiency in, you can take proficiency in another tool.
That gives you six in skills, two in tools, one in gaming sets.
Then, at level one in Rogue you get to add expertise in two proficiencies, but this doesn't add more, this only doubles your proficiency bonus in one of the skills you are already proficient in.
As a High-elf you get proficiency in Perception from the Keen Senses trait, as you mentioned.
This adds up to seven, which is the exact amount you should have. Plus two tool proficiencies, and a gaming set.
Best Answer
If they don't need to be concurrent, or always available, this can be achieved with two levels of Cleric in the Knowledge Domain, which grants:
It's not quick, but will legitimately grant you any conceivable skill proficiency in a pinch, as well as all tool proficiencies. And in the right circumstances, ten minutes can be a long time.