I’m confused & need help !!

I’ve been trying to conceive with my husband for the last year & we had no luck .. I went to the doctor at the end of last month & he gave me a pill called Letrozole to take when I started my period for 5 days .. & told me to make sure we had sex on days 9 , 11 , 13 , & 15 .. but that it didn’t have to be on all 4 days just those specific days .. we did it on day 9 & day 15 .. I took my blood work yesterday but they said it’ll take up to 2 weeks before I get the results back on my levels .. my app is telling me to check my pdG yesterday & im not sure what that means ? I’m due for my period in 4 days .. but I’ve been urinating a lot more than usual & feeling tired a lot .. I’ve been having back pains , & lightheaded alot more .. I just need help cause this is the first time I’ve tried any of this .. I never had a problem trying to conceive before with my other 2 kiddos ..