Bladder Pressure

I feel like I have something sitting on my bladder. No UTI. I feel like a constantly have to pee. I'm craving things I usually don't crave. Mild cramps. All PG test are BFN. I had what I thought was my period because it last 4 days and was normal flow from March 27-April 1. The last time I had these symptoms I was pregnant with baby #1. TTC baby#2 since December. It's not urgency like with a UTI, it feels like something is sitting on my bladder. And with baby#1, my blood tests didn't show positive until 5 weeks..Could I be pregnant, just too early to test? Has anyone had implantation bleeding that was like a period?