Do I have to commit to just one agent??

If your agents nailed the first five properties and then started missing the mark, the issue is probably communication, not commitment. Your needs may have shifted, their understanding of your criteria may have drifted, or the inventory in your price range and area may have thinned out. Before switching agents, have a direct conversation. Tell them exactly what's going wrong. The last several properties were over budget, didn't have the features you need, and weren't in the areas you asked for. A good agent will recalibrate immediately. If they get defensive or keep sending the same mismatched listings after that conversation, then it's time to move on. You're not expecting too much by wanting properties that match your stated criteria. That's the baseline of what an agent should be doing. But agents aren't mind readers, and sometimes what a buyer says they want and what they actually respond to during showings are different things. The five homes that worked might have taught your agents something about your preferences that the next batch didn't reflect. On committing to one agent, if you've signed a buyer representation agreement, you're working with that agent exclusively for the term of the agreement. If you haven't signed anything, you're free to work with someone else. But working with multiple agents simultaneously without telling them creates problems and usually results in worse service from everyone because nobody feels like they have your loyalty.

I recommend interviewing agents to see who has the expertise of the real estate goal you are hoping to meet and the knowledge of the area that you are looking in for your home needs. If you have already signed a buyers agreement with a specific agent and started working with them and are not happy with their process. TELL THEM, and talk to their broker so that you are getting the information you need to meet your real estate goals! They do not know if you are not letting them know. I always say not all agents are created equal. Not all of them have the knowledge of the real estate goal you are looking to accomplish. Not all agents are a good personality fit for your needs. So interview the agents you hope to work with in order to be sure it is a good fit.

Short answer: NO unless you have signed a binding agreement that contractually obligates you to one. Even then you may be able to use multiple if you are willing to pay multiple commissions. There is actually no need for multiple agents if you do your due diligence and communicate with your agent what you want.