@Violette22 I'm a consultant physician, nothing to do with fertility medicine but very good at reading research papers and coming up with plans!
The product you've found looks perfect.
You are right to be concerned about a low pH and getting pregnant.
This is an extract from a review where it's perfectly explained:
pH strips measure acidity/basicity. The pH scale goes from 0 to 14, where 0-6.9 is acidic, 7.0 is neutral, and 7.1 - 14 is basic. Lemon juice (pH of ~2) and coffee (pH ~5) are acids. Water (pH 7) is neutral. Stomach tablets like Tums (pH of ~10) and soapy water (pH ~9) are basic. (If you’ve never seen it, “~” means approximately.)
These strips only measure pH between 3.0 and 5.5. Per Dr. Google, a healthy vagina will have a pH of 3.8 - 4.5 (although your pH may be higher than 4.5 before menstruation and menopause). A pH over 4.5 creates the right conditions for unhealthy bacteria and yeast to grow, leading to BV or other infections.
In case you’re wondering, Dr. Google says a pH that is too low could create and environment where sperm are unable to thrive. Apparently sperm like a pH of 7.0 -8.5, which is annoying because we’ve already established that is prime caging all infection/bacterial overgrowth conditions. Ugh, men. Amiright?! (Ha, just kidding. I think?)
So basically the healthy vagina is acidic, it's acidic because the good bacteria are producing acid. Seminal fluid is alkali, under normal healthy conditions the vagina can cope with that, because it has a mechanism to reduce the pH (you don't currently have this as you don't have any lactobacillus). You don't want to put an acid tablet in there right when you're about to introduce sperm when you're about to ovulate. But you also need to get the environment right to allow the lactobacillius to colonize to get the normal mechanism working.
I hope that makes sense. My advice is, get the microbiome right before trying to conceive again. Keep an eye on your vagina pH, be mindful of where you are in your cycle if using the acid tablets.