Just today I was looking up information on how long a fertilized egg can live without implanting. The general consensus seems to be 12 days. So, at the latest, your fertilized egg would implant about 12 days after ovulation. Usually within 3-5 days of implantation, you can get a fairly accurate result. There are of course factors at play (like your resting hcg level) that can affect when you will see a positive test, but I'd say by 17 dpo you should be able to get a positive test. On the early side, a positive would show around maybe 9dpo.
Now all of this is assuming you have some way of knowing when you ovulated. Are you charting your basal body temperature? That is the easiest way to confirm ovulation, but by the time you see a thermal shift, ovulation has already occurred, so it's too late to start trying that cycle. OPKs are the best way to tell at home that your body is gearing up to ovulate.
I'm sorry to hear about your chemical pregnancy.
I understand that using OPKs on a super long cycle would be very draining. I guess if I were in your position I would do the following:
1. Track my bbt
2. Watch for indications of ovulation such as ewcm and an open cervix, when you notice these, take an OPK. Hopefully it will be positive, but even if it's not, BD!
3. BD regularly. Keeping your man's swimmers moving on a regular basis means healthier sperm. They recommend every other day, but that gets taxing after a while! My hubby and I BD'd one or two days on, one or two days off from AF to O this cycle, and I just got my BFP a couple of days ago. I think the frequent BDing is what did it, not just during the fertile window, but leading up to it.
Hopefully you don't need this advice and the symptoms you're feeling turn out to be a BFP for this cycle! Good luck!