The missed pill is a non-factor since that was SO long before you had sex. Whether or not being an hour late a few times with the pill matters is going to be determined by the type of pill you're on. Whenever you pick up a prescription, it should come with a bunch of fine print, including what to do if you miss a pill (and how much leeway you have in remembering to take it).
Cramping is common with some women before their period starts. Unless you're on a very light dosage of BC that has to be taken at EXACTLY the same time every day to be effective (most pills, I think, you have a few hours of sway to take it if you don't take it at EXACTLY the same time), I think you're probably experiencing PMS symptoms. It is not impossible to get pregnant on the pill (even taken perfectly, it still has a less than 1% failure rate) but EXTREMELY unlikely.
Rae (27), DH (26), Lucas (6/3/12), #2 due in December