Well look, I'm no bodybuilder, but at 5'07" I have come from being your weight to 145lb (give or take), so here's the advice I can offer:
- Yes, it's okay to be a lightweight, provided you are medically healthy and have normal function. Would you win many bodybuilding comps that way? No. But you don't have to reach a certain weight before you can be considered a man, or anything along those lines.
- I'm no nutritionist or dietician, and don't know the parameters of your allergic condition. As such it's very difficult for me to give quality advice on how you should be eating, but if you want to build muscle, aim for 1g protein/kg bodyweight/day, and increase total caloric intake by up to 1000kcal/day from what you're consuming now (500kcal to give an energy surplus, and 500kcal to cover the energy expenditure from the exercise you'll need to build muscle). All forms of meat --not just chicken-- have protein in them, as does milk. Likewise, legumes and various other vegetables have protein, however you'll need more of it to get the same benefit, and I'm told you'll need to be crafty in the way you mix and match them, as the protein available is allegedly incomplete.
- Make sure your exercise program is in check. Oftentimes, less is more, especially in exercise selection. If you can learn and master just 5 or 6 basic, compound movements, you will probably see greater progress than if you try learning 10 or 20 different exercises throughout the week. Part of progress is developing the motor patterns and learning the correct movement patterns, which will allow you to more efficiently move the weight, which will be more conducive to building your muscles. The more exercises, the less time spent learning each individual exercise, and the less effective the exercises will in turn be.