Yeah, i think if he is that busy it is understandable why he doesnt have time to text you back.. But you said he was your boyfriend of a couple months and he hadnt even contacted you nce in 3 days? I think that definitely shows he isnt really that interested. Just a quick call to see how you are doing would have been fine, but nothing in 3 days is not okay in my eyes. I think its probably in your best interest to leave too.
I am constantly busy, i work full time, single mother and i still have time to take a minute to call my interest once a day or so. Its not that much effort to ask for really. I would stop contacting him at all and see if he even bothers to contact you first. If he does voice your opinions and see where that goes.
You have all the weapons you need... Now fight!