I think it's really tough to compare lines this early on. Especially because the test lines get darker as they dry. So essentially you're comparing a 24 hour old line that has already started drying up to a fresh line that is still wet.
I did that very early on and drove myself nuts! I could never see a clear difference in the lines until I got to about 17/18dpo. Once I got all my blood work back I found out my HCG had been doubling properly, but it wasn't very apparent on my FRERs.
Oh, and my pregnancy cramps were worse than my period cramps!