There's also a product called "maybe baby". It's the most expensive pen light & magnifying glass you will ever buy, but I highly recommend it. It's about $100. (and no limit on number of uses, just replace the batteries)
It doesn't work for everyone and it's always a maybe no matter what, but me. my sis & the girl she heard about it from fell pg very quickly (< 3 mth) with it.
I had very short 'transitional' phase but could identify ov. I'm just starting to use it again. Fingers crossed