Fertility signs are doing my head in.

I think over analyzing everything must just go hand in hand with TTC cos my brain has been working overtime for the past 24 hours. I've been stressing about fertility signs and trying to figure out if my cycle is already a bust or not. I did an OPK last night and it was +ve. That's a 36 hour gap between my -ve blood test Friday and +ve OPK Saturday night at 10.30pm. Then this morning I woke up to a temp rise. So I have no idea whether I caught the surge on Saturday night at the start or the finish but the temp rise this morning has me worried. I did a saliva test and it showed full ferning - ie time to get busy with sperm. My clinic doesn't do IUIs on the weekend so despite all the signs suggesting I'm either ovulating or about to, there's no chance of inseminating! They usually use an antagonist to delay ovulation if they think it'll happen over the weekend but clearly on Friday it looked like we still had plenty of time. So I went in for the blood test this morning and told them about the positive OPK last night and they were like "Great!". This confused me since I'm freaking out at this point that I can't inseminate till tomorrow afternoon at the earliest (they also only do inseminations in the afternoon - can it get any more restrictive?!). So now I'm worried I'm missing my window of opportunity. If I caught the surge at the start and I haven't ovulated yet then a Monday afternoon insemination might still be ok. But if it was the later stage of the surge and I've ovulated today then I'm screwed. Anyway, they took my blood this morning and rang me later to confirm the surge and told me I'm booked for a 4pm insemination tomorrow. They've also cancelled the scan as it's apparently no longer necessary (probably because the egg will have already done a runner by then if it hasn't already!). I'm trying to stay positive but I'd be lying if I said that I wasn't concerned. I am just hoping that tomorrow morning my temp drops again or stays the same. A spike will be a disaster. I am relying on the fact that my temps have been all over the place for the last two cycles, I never ovulate this early, I've not gotten any EWCM yet and I'm only at day 12. But I've also never done injectables so who knows what impact that's had. I think I am just going to have to hope for the best and try not to stress that my little follicle has already flown the coop.