Would it help to know a little about what is being done to the biopsy to set your mind at ease that a delay etc isn’t necessarily reflective of bad news?
Once the biopsy is taken it needs to be sent to the lab to be processed. An endometrial (the womb lining sample) won’t take too long to be fixed in formalin as it’s small (larger samples could take a couple of days), it then needs to be embedded in wax, sliced into very fine curls, placed on a slide and dyed with ink so it can be seen under a microscope. All this can take a couple of days (maybe slightly longer if the sample arrives just before the weekend, the lab is short staffed, higher priority cases need to be processed first etc) and a lot of the process is done by hand.
The finished slide will then be passed on to the pathologist. It might be that the pathologist can look at your case (which it sounds like hasn’t been flagged as urgent by the team who took the biopsy based on your symptoms/what they could see at biopsy etc which is good) and be able to make a diagnosis right off the bat, type it up and issue the report. Or it might be that the consultant covering gynae that day has large volume of work including cases that are urgent so prioritises those and your case gets left for a day or twos time when things have calmed down (same way the sickest people are seen first in ED). It might be that a diagnosis isn’t obvious the the pathologist needs to ask for more work (different stains which highlight different things, more of the wax block to be cut into slides to get a deeper view, other special tests) - this can take a couple of days to a week depending on how busy the lab is and how time consuming the extra test is. Again these extra tests go back to the pathologist who then needs to find the time to look at them and write them up. A really complex case might need looking at by another pathologist which will add a couple of days.
What I’m trying to say is it’s completely normal for a biopsy to take a while to work through the above pipeline and it doesn’t mean anything about it being something nasty or not. You can spend a very long time on giving a benign diagnosis and spot something nasty instantly. Often the really nasty stuff is obvious straight away and the requesting team might be given a provisional result while stuff ticks away in the background so getting a result really quickly (can occasionally) be a worrying sign - or it just means you’ve got lucky with a straightforward diagnosis on a day the lab/pathologist isn’t that busy.
Apologies if you’re aware of all that but it’s often not explained to patients how much work goes into looking at samples and why it takes time so I think people sometimes get themselves worried about timelines when they don’t need to be. Even clinicians sending samples can have a warped perception of how long things take.
Spotting between periods is really common and while it should be checked out (so you’ve already done the right thing by yourself) by no means is it something that’s automatically sinister. I’d be massively reassured that the gynae was happy to wait as normally the more sinister stuff is apparent on their scans etc. Often we never find anything much and it’s just one of those things. Our bodies are incredibly complex and sometimes just get a bit out of kilter.
I appreciate waiting for a result is scary (I have an anxiety disorder myself) but it sounds like you’re having quite an extreme reaction if you’re not able to stop crying etc. Have you looked at any CBT/mindfulness stuff? Lots of examples online (your GP may have access to online modules/you may be able to sign up for them independently). It’s natural to be worried but at this stage it’s not helping. Worrying won’t change the outcome or how long it’ll take to get a result - you’re only going to make yourself feel awful so it would be good if you can find a way to look at controlling it. Reframe your holiday as a distraction - either you’ll most likely have had some reassuring results and it’ll be a celebration or you’ll still be waiting in which case what better place to wait than on the beach (etc - wherever you’re going!).