Having specific pregnancy symptoms but negative pregnancy test, could i still be pregnant?

I am on my first round of Clomid 100mg of cd 5-9 after inducing a period with provera. i had an ultrasound on cd 14 to check the follicles. I had 4 really good ones that were ready to go any day. then on cd 21 i had a progesterone test of 27 which the doc said was really good and indicated that i definately ovulated. so now i am on cd 28 and for the past 5 days my have been getting more painful each day. at first it was a dull ache and twingy and now they are so annoying that i constantly am aware that they hurt all over and my are EXTREMELY sensitive and always seem to be hard which is horribly annoying. this morning i tried a shirt on that usually fits but was so tight around my bust that i had to practically sqeeze out of it. also i am yawning almost constantly all day long and today i was so tired and sluggish that all i wanted to do was sleep which is what i have been doing everynight i get home from work. took a hpt on cd 27 and it was negative. am i testing too early and if so when should i test. my periods are always on their own schedule and usually only get them every couple of months. so to try and wait till a period is due to take an hpt is kinda hard cause i dont know when that would be.