Does rating increases in bulks or is it a steady increase? I have been taking lessons from a coach since two months and I also played my first OTB tournament two months ago. Since then I have played around ten tournaments with an average of one or two tournament every weekend.

Even though I have learnt a lot from every single tournament by analyzing my games with the coach, and I myself know I am more knowledgeable and experienced now then when I played my first tournament my rating has just fluctuated between 1000 and 900 throughout.  

My question is does the rating increases in jumps in general or is it like a steady increase where you increase rating points gradually playing every tournament? If its a steady increase, then I am sure I am not doing something right.

If I am 900 something after two months, is it a realistic goal to aim for 1500-1600 in the next 10 months, with coaching and playing 1-2 tournament per week?
Usually, in the beginning, the rating increase jumps quickly.  Just not hanging pieces could be a multiple hundred point increase.  As the rating increases, the rating increases become smaller.  This is because there is a smaller amount to learn, and technique improvement brings little gains.
Playing in this many tournaments doesn't really give you time to find and reduce your mistakes.  A coach can find your errors, but you won't be able to correct them within a week.  1600 is a realistic goal, and you should be able to reach 1800 within 5 years.