First off...there really is no correct level to be at for professions as you go. Yes, the skill caps open to 225 at level 20, but that in no way, shape or form means you should be at that level at 20. In fact, if this is your first character, barring help from friends/guild or buying all your mats, its not likely that you will be able to get many of the materials you need to level it that high on your own. So this isn't really a question of being able to "catch up" or being low in a skill for your level.
Secondly, if you aren't taking the time to farms herbs, its likely going to be the same for mining.
You also need to look closely at the combinations. What do you enjoy and what are you using it for. If using it for yourself only, both are fairly equal in value so you need to base it on what you like. Engineering is a lot of farming for various mats. The largest complaint I hear about it (but conversly why others enjoy it) is that it requires a TON of variety in Mats. One engineering recipe may require 6 mats, but to get each of those you need 3 to make each one, whereas something like alchemy you get you vials and on average 2-3 herbs. I would recomend looking at the recipes available for each, and deciding what will supplement you character and playstyle the best, both have pros and cons.
If you are using your profession for money making, I would recomend staying out of engineering. Most items made can only be used by engineers. If your an engineer you can most likely make the item, so why buy it. This leads to a small market and less sells. Herbs always sell well, and Potions can be used by anyone. Additionally, when you max out and are able to obtain some high end recipes you will find transmutes (arcanite, Water-air, etc..) and the flask recipes are good income.
Overall, don't expect yourself to have a certain skill level for you characters level. While its possible to hit 300 skill by 40, its a push and you have to be dedicated to the profession and focusing on it. On top of that, you expendatures for that push can become expensive.
Edited, Jul 24th 2006 at 11:00am EDT by FallonofDragonmaw