Pain in lower right side

[Rsal4]

So my period is 1.5 weeks late (roughly) and for the last few days I've had pains in only the right side of my uterus on and off. Today they have pretty much disappeared and its now just a tight feeling with pain here and there. No other symptoms and pregnancy test came up negative.

I never know when a good time to test is so if the pain was implantation how soon should I test and did anyone else have the same feeling?

It's quite likely just trapped wind or an irritated bowel on the right side afaik. I think when you're ttc you become hyper aware of every sensation that you might otherwise ignore.
If your period is late then a test at anytime is a good idea. Sorry you had a bfn, maybe give it another few days and try again. Then go and see your GP to put your mind a rest.