I think your comic is really strong! Your characters are charming and your art is really great! I love the bright colors and the story seems very cute.
The only critique I have is a technical one and it has to do with the lettering specifically. I'm just diving into the principles of lettering myself and can share some resources that I've found to be very helpful! I'll link to them below. Essentially I think you can work on the following in regards to lettering:
1) I noticed a couple instances where balloon tails overlapped or were layered over or behind or merged with other balloons. Try and avoid doing that as much as possible and stack your dialog in such a way as to make a clear separation between the two speech balloons. Too much overlapping of tails can be very confusing and will cause a reader to have to stop reading just to figure out who is talking. I've done this myself and have been trying lately to correct that in my own work!
2) The goal of lettering is to blend into the comic so much that it becomes invisible and the art and story are the focus. I found myself more focused on the balloons and speech bubbles than I was on the art, especially as I did a quick scroll through to get an overall impression.
3) Try and stick to one thickness for your balloon tails at the point where the tail meets the bubble and keep that consistent throughout the comic. It just looks cleaner and adds a level of consistency to the work overall!
4) Try and stack your dialog in the balloons in a diamond like shape with your longest line of text in the middle of the balloon.
5) Be mindful of the fonts you're using and avoid using too many different fonts for dialog. Avoid serifed fonts for balloons as well. Go crazy with fonts for sound effects and the artwork itself though. ^^
Aaand I think that's all I have! There's a reason why there are professional letterers out there. It's an art form in and of itself and is very difficult to nail down. You're doing a great job and I think once you get the lettering to be more consistent you'll be golden!!
Here's those links for you:
http://www.balloontales.com/category/tips/lettering/