I’m employed by a charity and work closely with the shops, I wouldn’t be worried at all - your donations have definitely not disappeared and the charity will do their best to sell everything they can to raise as much money possible!
As you dropped the items off a few weeks ago, they have probably already been sold - depending how busy it is, items can literally be put out for sale and sold after barely touching the rail/shelf.
Or they could be in the sorting/stock room, waiting to be sorted, steamed, priced and then put out for sale. There’s usually mountains of donations waiting to be sorted, most charities rely on volunteers to help and there’s just not enough time to sort items as quickly as they come in.
With higher-value items, they may have been put up for sale on eBay, depop, etc. Sometimes individual shops will do this themselves, others will send the items to the charity’s distribution centre to be sold by their e-commerce team.
If they’ve been on the shop floor for 2 weeks and have not sold, then the items will be ‘culled’ and sent to another shop.
They’ll also send items to other shops if they have too much of something, like menswear, whereas another shop might be short. Or if it’s a high-value item, it might raise more money in a high-end/vintage shop, so they’ll be sent there.
If items are not in saleable condition, textiles can be sold in bulk as ‘rags’ and other items recycled (but it sounds like your donations were in good condition, so that’s probably not the case!)
And if you’re a Gift Aider, you will receive a summary letting you know how much your items have raised, I believe it’s an annual statement but I’m not 100% sure.
Most charity shops will now ask you what you’re donating and will tell you if they’re unable to take it. It costs the charity money to pay for waste removal and sadly lots of people do not realise this. So, if the charity accepted your items - that’s a good sign!
If you’re unsure about donating in the future, then you could sell the items yourself and then donate the money to a charity of your choice?
Anyway, I hope that helps!
(On the topic of charity shops - does anyone else follow a FB group called Charity Shop tit? It’s absolute gold!)