Salary question

After nearly one year's searching, I finally got an offer from a very small company. Actually I didn't negotiate anything before the employer sent out the emplyment agreement. The offer (the same as my previous job)is almost 10% lower than my previous job without any benefits. I was told that my insurance would be added and my base would be increased to my previous level after three months. However, this was not written on the agreement. Could I negotiate? I am not young, so it may be harder for me to switch a job. Please advise. Thanks!