Cheeky
It's horrible isn't it, sounds similar to what I went through last month. I was 6 weeks by dates but it was never quite right. I kept getting faint BFPs for ages even after I was late and then had low HCG level when it was tested (which is standard at booking in in Germany which I did at about 5 weeks by LMP). HCG was 99 which suggested 3-4 weeks. They couldn't see anything on a scan then and suggested I might have ovulated later, which is what led me to obsess over HCG levels!
I didn't take any digital tests but I did do some research on them because I was considering it but the cost was putting me off especially as I had access to blood tests etc. I was thinking maybe there was some hope for you but I think probably when you take the whole pattern with the EPU blood test into account (though they really should have done two) it doesn't look that good does it :( Sorry.
I will include this anyway as it might be helpful to you (first review explains how the weeks estimator thing works and the margins of error)
www.amazon.com/Clearblue-Advanced-Pregnancy-Weeks-Estimator/product-reviews/B00D05VGCS
And for comparison here is the most helpful HCG chart by day that I found.
www.babymed.com/is-my-hcg-blood-level-normal
You can see that there is enormous range even within one day which is why they say that only blood tests can tell you accurately what is happening because you need to be tested 48 hours apart and see how fast the levels are increasing or whether they are.
In terms of what to expect, I had spotting for a couple of days on and off (which was horrible because I kept feeling like it was okay and then being sad/anxious) and then it was exactly like a period for me. I normally have light periods and it was heavyish but I was only really needing one or two pads a day. I didn't suffer a lot with cramps. I was having pelvic floor pain towards the end (that stabbing "javelin in arse" pain) and I was really constipated and then made it worse because I was a bit scared to push when it was all happening
I reckon if I hadn't been two weeks late I wouldn't have known it wasn't a normal period. I didn't see or feel anything resembling a sac in what I was passing but I wasn't really looking at the toilet paper etc. But certainly the event itself wasn't distressing or painful, only emotionally of course.
I think see how you go with work etc. I found the whole thing was okay, overall, but I definitely had a couple of days where I needed to hide under the duvet and do non demanding things and I was lucky in that my job allows me to do this. In terms of the actual bleeding it wasn't debilitating and it only lasted about a week altogether.