Well I'd like to examine this in two ways. First, on the left, they are a tad bigger than plentiful handfuls. On the right, they are a tad bigger than your head!
Also, another tit measurement I like to use is the elbow test. When your arms hang at their sides, you measure how far past your elbows the titties go. On the left, your elbow is clearly a little lower than or same length as the boobs, while on the right, your funbags come down far past your elbows. Of course this all depends if your are wearing a bra or not which I assume you are not in both photos, therefore there is no error in the measurement.
All in all, there has been significant growth over the past year for sure. Keep it up cuz it's so damn hot!!!