I weave my own hair by braiding it first and then sewing on the tracks and I'm pretty good. I just find that, before I sew on the tracks to the braids, I first sew my cornrows but how do I do that without making it bumpy looking?? When I put the weave in a ponytail, it looks just a bit bumpy in some parts but it looks fine when I wear the weave down...

Your row is not tight enough. If you can sew it where the two braided rows come together first, then sew the rest of the cornrow you shouldn't have this problem. But there is always a little bit of a problem when you use tracks and try to wear a ponytail, the hair has a 'seam' in it, so you have to tie the pony tail under the track row.