Need some advice please :(

Hello guys, New here

So I recently went to my local fish store and spoke about discus fish, I have had discus before but they required alot of hard work as they do lol. Anyway I had a 240Litre tank sorry im in the uk with 6 discus, but there was a smaller one that kept being bullied and I had to remove him and place him in a 125litre tank and he loved it on his own with some tetras and a dwarf gourami which he bullied lol 😆 anyways I wanted to get back into discus as I've got alot more time on my hands and I do miss them....

So I went to my LFS and saw the 4-5 inches discus they was 29.99 GBP. So me thinking about the 1 in the tank that I had to pull out due to bullying, I brought 1.... now I'm regretting it.... he seems lonely hiding all the time but he's pecking at food which is good. I could be paranoid... I know these are schooling fish and now I wish he stayed with his mates in the store... currently I only have a 140l tank but I have ordered a juwel rio 450litre which will take a month to arrive. I feel he shouldn't of sold me the fish because I told him he's the only one but I'm blaming myself to.... after alot of research and everything... I've found new stuff like German captivity and asain and that they shouldn't mix... I don't even know which one mine is... i will do water changes every other day for him. I'm not sure what to do I don't know if to get 2 more and overcrowd for a month till I can get them in the new big tank or take him back.... lose my money but better than letting him suffer... or dieing

Can i get some advice please on what you guys would do.

There is 4 clown loaches babies and 7 tetras also

Temp is on 82F
PH 7.2

Just done a water change before putting him in today

The picture was when he was first let into the tank now he just hides and doesn't come out

Thankyou so much
Sonia