Calculators show I am 75k-100k better off renting than buying over 5 years and I'm freaking out (middle of purchase)

My main reasons to buy were to no longer deal with BS London rental market and to stay in the area I like so I knew it was emotional more than financial decision, but damn i didn't expect it to be this bad. It gets slightly different with time but I don't see myself staying in that flat more than 7 years tops.

I think the main reasons for such a dramatic difference are:

- I am perfectly happy to rent a small 1BR but am buying a 2BR, considering everyone I know who bought 1BR found it a nightmare to sell (a lodger is not an option for me unless emergency). I estimated 12% annual increase in rent for calculations (I never had a rent increase in 6 years of 3 different landlords and just negotiated really good terms on my current rental)

- it's an ex LA flat in a tall block in Central London , so I do not expect it to gain in price given the ruthless studies on flat prices (I am also buying it well under asking price but still overpaying 10k on bank valuation). I also budgeted 10k vaguely for major works risk in next 5 years. Non ex-LA flats seem to all have massive service charges and their own problems - i looked for that mysterious share of freehold flat with RTM but was unsuccessful

- I have a larger deposit and am able to save a lot more right now than I would after buying, so even a modest return on investment adds up.

I know , I know it's a home not an investment but the value difference is just staggering. Does anyone have any thoughts?

ETA: posting rough numbers based on the advice I received below.

Current housing costs (not including utility bills or council tax for simplicity): rent 1750 pcm

Current savings: 120k earning 4.2% interest on instant access account but if I wasn't buying I would get a different investment vehicle

Further savings each month (before purchase): circa. 1,750

Flat cost: 506k. NB: in London, to afford a freehold house for this price I would need to move far out and nothing about house ownership appeals to me or my disability

Deposit: 96k

Purchase costs: roughly 18k including solicitors fees, stamp duties, removals, bank fee and some immediately necessary kitchen upgrades, furniture and incidentals.

Mortgage payment: 2150 pcm (rate 4.45%), service charge 175 pcm. Estimated repayment towards principal in 5 years 35k/40k.

Home ownership cost of repairs: I budgeted 2,500 per year, + 10k towards potential major works risk in the next 5 years (not currently scheduled but i think it is highly likely). I would also need to save towards that aggressively as the purchase will wipe majority of my savings.

ETA2: i think another cost calculators factor in is selling cost for the flat which is another 20k wiped.