Hi, I'm also watching our young corn (Audrey) progress well and coincidentally also got her in early November, at around 8g weight. I've been lurking as a non-contributing reader on this forum for a while (sorry to be shy folks!), but my day job is as a scientist (an animal physiologist) so in addition to a fascination with my newish pet, I love monitoring stats and modeling things and have kept very careful records. She's a well monitored snake
At present my girl (I think she is a girl) is ~45g, so only about half the weight of yours. But her smaller starting point is significant: she took her first month to reach the 14g yours started at. .
Several factors will determine growth rate, obviously all limited by the rate and size of prey you feed your snake, since in captivity they are not free to feed at will, but get their nutritional intake at the rate we set for them. One of these factors will be genes (including his/her sex): some snakes (like humans!) will just grow more slowly than others despite an identical diet and may end up as smaller adults. There is not necessarily a 'right' value. But other factors can also make a difference: since snakes are ectotherms (they get most of their body heat from their environment), tank temperatures will affect both their metabolic rate as well as their digestive efficiency. These in turn will affect how much energy they use between feeds (weight loss) and how much they gain from each feed. Nutritional quality of the prey can also vary.
Having read the advice of many others on these pages, I've been following slightly less aggressive intervals than the 5-6 days that the Munson plan suggests for this size range (e.g. I've been giving 6-7 days between feeds, and a few times I've skipped a feed when she's been in blue). She has been gaining a very steady 31% of the prey weight at each feed. If you've been using shorter intervals (as per Munson) you could expect the average % gain from each feed to be higher. As Karl notes above, some folk report weight gains in young snakes of around 40% of the fed prey weight, but less in near-adults that are typically fed prey that are a smaller % of their body size and at longer intervals.
If you model Munson plan feeding at the slightly less aggressive end of the range suggested (i.e. assuming mid size prey for each of the stages and using 6 day intervals) a snake starting at 14g in early November would grow to around 68g over the ~135 days if you assume it retains ~30% of the feeder weight (as does my snake). This would be more like 92g if it retains 40% of the feeder weight (as per Karl's Rufus). Hence while your 90g is at the upper end of the range, it doesn't seem very surprising if you are following the Munson plan.
