Jumping straight from nothing to all at once is usually a recipe for disaster.
Out of curiosity which butt plug did you purchase?
Using a butt plug or anal tool before having your boyfriend go inside is a really good idea, to dilate you a bit and not have a dramitic jump in size difference (nothing to everything).
If it was a lot of blood, then I would refrain from having anal sex of any sort for at least a week-week and a half, 2 weeks preferably, to be sure that the anal passage has healed before trying again.
If you find you are having trouble/pain with passing stools or finding blood in your stools, then you must see your doctor as soon as you can as you may have done a fair amount of damage.
If it happens to be a fact that your partners dimensions are just not going to work for you, then you may want to look at the sex toys available here for him to use on you. Not quite the same, I'm sure, but at least you wont need to give up what you love entirely. But I would make sure he is aware of your issue, incase he wonders why you aren't interested in anal sex with him any more.
Good luck, and take care. xx