Just to clarify, day 1 of your cycle is when your period STARTS.
Normally you will ovulate SOMETIME between days 11 and 16 of your cycle.
The egg is viable for 48 hours after ovulation and sperm is viable for about 5 days.
You had sex on day 17 of your cycle so you'd likely already ovulated. It is possible that you could conceive. There is a chance that the light cramps are "implantation" cramping. You may notice some very light, no pad needed, spotting. This is another indicator that you MAY be pregnant.
It's early to test. You need to wait at least 2 weeks, preferably 3, after having sex.