As you have completed your graduation in Mechanical Engineering, there is no need to get upset or disappointed. Afterward, you have many options to build a good career in your future.
As far as the current situation is concerned, if you are getting a job offer in some companies by some consultancy, then it would be a good choice but if you have salary then a little negotiation can be done in any consultancy. First of all, if you are satisfied with your interest in work or how your job profile is, then you should be a little flexible at the beginning of your salary. As you said that these companies are giving you around 18 to 20 and your expectation is 22 to 23k in hand, so there is not much difference. If your job profile looks right to you, then soon you can get increment based on your work capacity and hard work.
Apart from this, you have many options, which will help you get different jobs depending on your degree.
In the government sector - as you would know that there are many government enterprises where there is a great demand for a mechanical engineer, for this you can also take full information from the government website. You can get a job after an examination and after a good performance in an interview.
Control and Instrumentation Engineer Automotive Engineer - If you are interested in this field then you can also think about this will also be your option. They are in great demand in many large factories.
Maintenance Engineer - As it is your own in the subject of mechanical, you will have enough maintenance information. If you want, you can also pursue a career as a maintenance engineer.
Architectural engineering - is a very emerging field, as if you are also interested in design, then think about it. The main task in this is to rebuild a built structure or to build a new structure.
Drafters Material Engineer - In this job, engineers use design software to convert designs created by engineers into technical drawings, this helps in designing microchips, etc.