Vinyl Hell

Thank god the wall decal in Oliver's room is finally completely up. I got it on ETSY and absolutely love the design. But it was so intimidating - large and in so many pieces, so it turned into one of those painful projects that just gets dragged out. And then, it started peeling. I think it's the textured walls and slightly matte finish on the paint. Ugh. Whenever I am nursing in there and notice a corner peel up or a ripple in a part it drives me nuts! I stick it back down, but inevitably it will pop back up. I've considered wallpaper paste or a clear coat of paint. But I really don't know what is the best plan. I would like for it to last a few years. I just want it to stick! Suggestions?? Oh, and isn't it cute?